You could always get some plastic for your pickup Fran, make a temp pool.

(Redneck pickup pool).
All it costs is some plastic, is temporary, and saves you from heatstroke. Lots of people actually do it (google it) when it's extreme heat. And you don't have to have another type of pool to store or maintain. Because temporary. Someone even sells it as a product/kit.
Just a thought. It's fun to look at the pics too. Takes a bit for the water to warm up though, I'm sure.
I haven't tried it, I don't have a pickup otherwise I probably would have done it just for the hell of it.
Goodnight snails.
EDIT: Be careful of weight/capacity though.
NO SWIMMING: Why turning your truck bed into a pool is a terrible idea (VIDEO)
Maybe support the frame with jack stands. Ask Hubs.