You can get liquid lexatron from Sotar if you are running a urethane boat, it's good for pinhole leaks and comes in every color they made rafts in. You apply it to the pinhole leaks or around patch jobs. A little bit goes a long way and the stuff dries up pretty fast in storage so use it all when you get it.
As far a painting a raft to improve looks, I think that's the worst idea I ever heard. If your boat has a lot of grey spots you can get some MEK at the hardware store and use it sparingly on things like scuffs and frame marks but be aware that the stuff is actually stripping a thin layer of urethane off and revealing the better looking urethane beneath it. I have done it to get frame marks off and also to remove logos.
Just find the pinholes with soapy water, mark them with a marker or with tape if they are in an area you can see, then clean that area good with MEK, then while the raft doesn't have much pressure in it, apply liquid lex with a brush. They have liquid lex in all the colors that their rafts come in.
If I wanted to improve a Sotar to handle wear I might consider installing hypalon runners on the bottom running the length of the boat along the waterline if there is a lot of wear, or even ordering lexatron patches to do this same thing with- if you do that then the boat will remain slick on the bottom- one of the best things about Sotar, but other than that I wouldn't mess with it. It is hard to get anything to stick to the super-slick urethane, patches, paint, anything, so I would be very concerned that any brush on treatment would not stay on long, I certainly wouldn't expect it to improve looks.