Invent such an item, that is compact, lightweight, easy to use, and maybe even somewhat affordable., and you can become a gazillionaire!

Joking aside, I wish there was such a thing, because I sure could use it on the electric airboat I will be building soon. I haven't found any, just like I haven't found a good way to put a very low profile (for prop clearance) waterproof hatch on a boat that doesn't involve screws. Kinda quite difficult to securely glue Tupperware type plastic.