I just purchased a used fiberglass kayak. I am wondering if it is a bad or good idea to use spray foam insulation into the bow and stern and not use the air bags? The foam floats and is not very heavy. The kayak is all fiberglass. I am new to the sport and have only used the kayak once but love it and am looking forward to many long rides.
Any suggestions would be great.

I also want to paint it can you use spray paint? What kind? Color?
Thanks
Chris