Everytime my inner boots split, out of frustration and desperation, I too was looking at the split boot route. I was seriously considering this because I just wanted an easy fix.
But after calming down and some reflection, I decided that I felt more comfortable just removing the axle by the tri-lobe area and the circlip.
There was no way I would be able to clean the area enough and then glue the two pieces together on top of maybe it not fitting right. I will not glue it competently and the threat of having to go back in there to refix it again just made me buy the oem boot. I have a tough enough time squeezing the grease into the boot and making a crappy mess. Of course THAT repair didn't last and it splits again.
Anyways, me being tired of going back in was the reason i decided to just get a whole new axle last fall, because my new oem boot probably split perhaps because of the lift. 2nd back to back oem boots by the way,
Then after the recently new oem driver's axle boot decided to split yet again, after that I felt the low of the lowest, I had to do yet another 3rd boot repair. So I mentally regrouped this time and used a flexi boot and utilizing the original tri-lobe part of the oem boot. This way you can use other boots that don't originally fit. I wanted to try a more flexible boot than the stiffer oem since I have a lift. So far so good. I also have a high angle boot as back up even though there is no space for it. Dang balancer in the middle.
I do have a high angle boot on the passenger's that has given me no problems. My OEM axles have lasted 13 years, they are real hearty and durable. Seriously, I didn't need to replace the driver's side axle but I was mentally drained from having to change the boot so soon.
The great thing about the older axles is that the rollers are secured and don't fall off when you take that part out. No biggie but convenient.