Well it is a success! All wired up and thumping like a beast, many thanks to Vstar60CL for insight on this, I couldn't have done it without it. Well I probably could have but it would have taken a LOT longer
. For anyone else who wants to do this, at least with a 2013 Rogue with the Bose/Navi sound system, after you have disconnected the negative battery cable of course, all you need to do is solder a single RCA jack to the tan and yellow wires, pins 9 and 14 coming out of the left side connector and your remote on/off signal at pin 25 of the right connector that plug into the BoseAmp behind the rear passenger's side seat under all the interior panels. The BoseAmp is mounted to the body right there so the easiest point of ground for your amp ground is to sand any paint off the body under where the left side mounting bracket point that holds the BoseAmp to the body, replace the bracket and use a ring terminal between the bracket and the nut that secures the bracket to the body. I only needed about 4 feet of wire to get to my amp and leave a little room to move it around.
The easiest way to run your positive power wire is, unfortunately, to remove the battery and the platform that it rests on in order to remove the air cleaner box. Be careful when doing these 2 steps because there are a lot of wiring bundles and electronic devices attached to the battery platform. I used needle nose pliers to dismount the plastic nipple style clips that hold the wire bundles to small holes in the structure of the platform. There are 3 nuts that are a little bit difficult to reach and the studs/bolts that are there to secure them are way too long for their intended purpose so when I re-installed the platform, I swapped them out for shorter bolts, just in case I ever have to remove it again. Hopefully I don't. Anyway, once the air cleaner box is up and out of the way, there is a very large rubber grommet that seals the main wiring harness that goes from the engine compartment into the interior of the vehicle in the firewall. I'm on the short side so it was a little awkward to reach it but taller people probably won't have this issue so if you are shorter than 5'!0" or so, maybe you can employ a friend as this job would definitely be easier with 2 people. I got it done on my own but I had plenty of time to do it and have patience so it wasn't a big deal. If you are pressed for time and/or have little to no patience, I would definitely recommend getting a helper.
So, once you have located the wiring harness grommet, take an awl, screwdriver with a small sharp tip, or any such tool and puncture the grommet to your left side from standing in front of the vehicle, or toward the passenger's side of the grommet. If you do it top, opposite side or bottom, which are all harder to reach anyway, you will have a hard time getting the wire through into the cabin as the grommet is either a 2 piece unit or it is shaped in a way that there is a "baffle" for lack of a better description, and the wire will just keep moving around between the 2 surfaces and you won't be able to grab the end from inside the car under the dash. if you do it where I've mentioned, there is a gap that's open enough to get your fingers into and grab the wire. It's not too hard to find the grommet under the dash, there's a bit of insulation to navigate through but once you can feel the metal of the firewall, just keep moving your fingers around and you'll find it, it's almost directly behind the tach, maybe a bit lower and once you find it, if you move your hand around to the side where the wire has been pushed in, you'll be able to feel for that gap in the inner rubber part of the grommet. Open it up a little and the wire should be right there. Pull it through a ways and it's time to start the route. I went up over the wiring bundle just above the emergency brake pedal mechanism and came down the outside edge of it and through the plastic hole that's at the very bottom of the wiring harness holder that's there for the wires that go to the rear of the car and then it's just a matter of popping off the plastic door jamb kick panels, the b pillar lower panel and routing it through the existing wire harness guides. Then there is a small panel that you can pop out of the plastic panel that's behind the rear door and if you keep pushing the wire up into that area from below where you have to push it from, you'll be able to find it and pull it up through there a bit. You could pull it the rest of the way through and go to the back of the cabin from there, but my amp happened to be mounted to my box toward the passenger's side of the car and that's also where the rest of the wiring will be when that part is finished so I removed all the trunk interior parts and continued to run the wire under that panel and across the car through the tunnel for the existing wire bundle. Once the wire is where you want it, it's a good idea to take some zip ties or equivalent and secure the power wire here and there along the entire route to keep it from vibrating and otherwise moving around as this can rub the insulation off the wire and can cause a short. If you don't have your wiring properly protected against short circuit, could also cause a serious fire. That's why you'll want to use a fuse or circuit breaker properly rated for your power wire mounted as close to the battery as is convenient. The recommendations are between 12 and 18 inches but that's not quite as important as finding a suitable mounting spot as not all vehicles have a place to mount this device that close to the battery and it's more important to have it securely mounted to the body of the car than to have it exactly in that range because if you were to mount it 12" from the battery but it is loose, it can move around under the hood while you are driving and that's not a good situation for various reasons. On my installation, I have it screwed to the inner fender metal just front of the strut mount tower. It's about 2 feet from the battery but it's not going to move and I secured the wire between it and the battery at various locations to minimize any movement. If you maintain your vehicle as you should there are plenty of opportunities to give it a quick inspection to make sure it is not wearing the insulation off anywhere or moving around. Any wire from the fuse/circuit breaker back to the amp is now protected.
Now for the rest of the install, as mentioned at the beginning, strip a small section of the insulation off the tan and yellow wires that go from pins 9 & 14 of the 14 pin connector that goes into the driver's side, or left port of the BoseAmp, about a half inch or so and solder the leads to a single rca jack to the bare part of the wire where you stripped the insulation. The yellow is positive and the tan is negative, and these 2 wires will be the 2 that are in the connector to the far right of it, or the 2 wires at the passenger's side end of the connector if you don't know which pins are 9 & 14. Those will give you a mono or single channel subwoofer signal to run to your amp. If you want it split into 2 channel, or "stereo" simply "Y" cable from that and there are your 2 rca jacks for the amp. The other wire you will want to tap into in the Bose wiring harness is for your "amp on" signal which turns on your amp when it detects a signal from the audio system so that the amp for your subwoofer isn't on when the audio system isn't on. This one is a small green wire with silver stripes on it and it is the wire that goes from pin 25 of the right, or passenger side BoseAmp connector to the subwoofer amp for the Bose "subwoofer" in the spare tire enclosure. For those that don't have a wiring diagram, pin 25 is the 3rd one from the left on the bottom row as you are looking at the BoseAmp from the rear of the car. Solder the wire from your remote on/off terminal to that wire and you are done in there. make sure all your soldered connections are properly insulated with heat shrink or equivalent, use some good quality automotive electrical tape to re-tape all your wiring bundles back together, replace any cable protection that you may have removed in order to get to these wires and replace all the interior panels while routing your wires so they will be in convenient reach for the connections to your amp once everything is back in place. Once this is all complete it's simply a matter of connecting all the wires to their corresponding terminals on your amp and you're ready to bump the Bose with a real subwoofer.