Vanlife product company Mogics has developed the Vanlife Tube, a watertight rig that allows you to shower inside of a minivan. It consists of a flexible tub that breaks down to just 12" in diameter, and which can be easily drained afterwards.
This all sounds wildly unlikely, but I was impressed at how do-able it all seems in the demo video. Was also impressed at how he stretches the water supply (a mere 2 liters, just over half a gallon) by using a pressurized spray canister:
Enter a caption (optional)
They don't say anything about water temperature, so it's on you to devise a way to warm the water before you load the canister.
The Mogics Tube runs $60.
Join over 240,000 designers who stay up-to-date with the Core77 newsletter.
Test it out; it only takes a single click to unsubscribe