I got lucky add ran across that very same atv mount sprayer at Walmart marked down to $35 bucks a couple years ago, planning on using it on my camp-trailer buildI am putting together a DIY shower and kitchen wash:
ATV Sprayer w 12v pump to connect to my dual battery system that I have in the rear:
changing the head to this:
and a heating element that ill connect to my portable generator
might add an water input system with a pump and filters later for drawing water from rivers/ watersource for longer stays.