I don't think the cylinders would hold fuel forever. The fuel will seep past the rings and into the crankcase/oil sitting overnight. I'd change the oil when you're done with all of this. It wouldn't hurt to check the oil level just to be sure it's not overfilled, if by chance you had a massive amount of fuel leak in to the crankcase (unlikely). As a side note, you may have a rough or bouncy idle for a little while if you had fuel wash the oil off of your cylinder rings, because you won't have compression on that cylinder until the oil gets back on to the cylinder walls and helps those rings seal.
Here's the TSB that I mentioned. There's a graph that gives a good feel for what's normal with fuel pressure leaking down. I would probably skip trying to pinch off fuel hoses unless you detect a leak. Then you'd want to pinch off the return line to see if that's your problem. Or you could use a small scrap of hose with a bolt clamped in to it as a plug for the outlet at the rail, to avoid clamping and possibly damaging the fuel line.
The TSB and old thread is for the 90-96 series of Q, but I would think the specs are about the same for all of the Nissan side-feed style injectors.
https://drive.google.com/file/d/0B-M9Hn ... y=CJHR2qkF
Here's an old thread talking about testing the rails off of the car.
testing-injector-seals-in-the-rail-coul ... 66243.html
And here's a pretty good Youtube video of a guy doing it on his Frontier.
https://www.youtube.com/watch?v=qJ7L9aqEcfM