Les,

I have used Automotive clear coat over West/ 207.
It is very clear, as Dan said.
Two part urethane, I have both sprayed and brushed.
The only issue was my poor application skils.
It can be sanded and compounded/ polished to a perfect gloss.

I used a cheaper brand, only about $100/ gallon. I can find the brand if you want. Some automotive stuff exceeds $400/gallon.
My assumption is that the kayak would typically be out of the sun for storage, so less than perfect protection will still be good.

Just a note, I was able to spray a coat, let it set up, then spray another coat while having left the material in the gun pot. I didn't clean the gun between coats. Might be risky, but I had no problems.