If you have access to water and a 110 VAC electrical supply nearby and an easily constructed privacy curtain this works well. Heats 5 gallons of water in a metal bucket in about 15 minutes. I have used one of these for a few years at one of our remote soaring locations. 5 gallons provides a luxurious bucket bath.

https://www.amazon.com/Allied-Precis...er+submersible

Disclaimer: I was a soldier for 20 years so my idea of luxurious may be slightly skewed.

Ron Clark