I also put my information in the INSIDE of my aire boats. I make a laminated card and put it in between the bladder and the shell. I asked Aire before doing so, they say its no problem. Maybe its overkill, but if my boat gets stolen, its pretty easy to get sharpie/serial number off, but the average thief isn't likely to check inside the shell.
I do something similar with my NRS frames. Laminated card rolled and taped to the inside of one of the pipes.
Only slightly related, but I also keep an organized file of pictures of all my major gear with serial numbers when available.
but can you see its opposition | comes a-rising up sometimes | that it's dreadful and position | comes blacking in my mind | ....and then I see a darkness