Tony: When I've done it, I've rolled as much of the tube over top of the inside of the rigid bottom, placed the cover or tarp over it and gently strapped it over top with motorcycle straps. It ends up kind-of like a scoop of ice cream in a bowl. Bungies are OK, but you need to keep the hooks off the tubes. If you're worried about length of time ore the tubes drying out, lube it up with tube conditioner or vinyl & leather automotive stuff. The straps help make it manageable when you need to lift or move it. I haven't seen any extra wear and tear from storing it.
"I'd rather be happy than dignified".