You guys must have to much money
We use a galvanised bucket, heat the water up on any heating sort to your desired temperature (around $10). Buy a 12 volt portable jump starter, if you do not already have one, about $70. A 12 volt shower unit, $30, but throw away their pump and buy a TMC 12 volt in line pump, $50.
The bucket has many uses, we cook our yabbies in our hahahahaha, the jump starter can start your vehicle, plug in a 12 volt light to it, and the in line pump can be used to transfer water. All up around $160.