It figures, you're shorter and get the taller rig...
Here is a way you can have hot water and not use any power other than idling your vehicle for a few minutes. However, it will require a 12VDC pump.
Back in the '80s when I was big into off-road 4x4 truck camping, I took a marine heat exchanger, brazed 5/8" barbed fittings on each end, and mounted it under the hood in line with my vehicle heater hose, with the radiator water flowing through the larger tubes. Then, I plumbed the smaller tubes to the rear of the vehicle and connected one side to a 12VDC SureFlow pump with the pressure demand electric valve. This became the intake side of the system. The other side became the discharge side and was connected to a handheld shower sprayer with a on-off valve. With this setup, the pump only pumps cold water and not hot which will damage the pump itself. I bought the heat exchanger at a marine surplus store for something like $20.00 back then, and it's made out of solid copper. It's about 12" long and 2.5" in diameter.
When you wanted to take a hot shower (and I do mean HOT), you just dropped an intake hose into a bucket of water (
or your water tank), stream, river, etc. and cranked up the truck. In a few minutes when the engine warmed up, the water flowing through the exchanger from the pump would be plenty hot to shower with even in the winter time. With the older vehicles, we found you could change the water temperature somewhat by turning the vehicle heater on, and using the temperature slide control, which would determine how much radiator water flowed through the heat exchanger.
Eventually, we found the best way to set the water temperature was to use a 6 gal plastic water can full of water (
or your water tank), and keep recirculating the water through the system and back into the can until you reached the temperature you wanted. This usually only took about five minutes. Then shut the engine off and pump out of the can (
or tank) to take your shower. I built a nice looking control panel and mounted it under my rear bumper, next to the receiver hitch. The panel had a power switch and pilot light for the pump, and intake and discharge 'quick connect fittings' using 3/8" pressure washer fittings.