Thanks for the input Zach. Whenever my raft isn't on the river, it's lightly inflated on my trailer in my side yard and covered with a car cover. The car covers fit really well, block UV, are breathable and cost about $40 at Walmart. They aren't waterproof, but they do breathe and dry quickly. So far I'm happy with this approach over the 303. I didn't do any 303 this season.
"We are all visitors to this time, this place. We are just passing through. Our purpose here is to observe, to learn, to grow, to love....and then we return home."
Australian Aboriginal Proverb