Kerensky97
Xterra101
It all depends on how powerful the sun is. The volume of water amazingly keeps the temperatures lower than you'd expect. If you want "hot" water and you're not in 120 degree heat a black container would be better. Or paint the can black; we did that to some in the Army for the same reason as you. The paint doesn't stick really well and they'll end up looking super beat-up in no time but it makes a small difference heating the water.Does the water in these tan/sand-colored water cans get hot if you leave them in the sun all day?
Hoping to use one as water storage for a camp shower.
However that wall all just trying to adapt the materials at hand to jury-rig a camp shower. I'd recommend just getting a cheap "camp shower" designed to heat the water and filling it from the can. Purpose designed gear is usually a better option and camp showers are cheap.