Shran, I spied a camp shower in your tote. How do you like it? I've been considering something like that for two reasons:
1. My wife doesn't like going without showering. This limits our camping opportunities a lot. There is a ton of state forest camping around but they don't have showers. Less of a problem in the summer as we can use the solar shower and/or lake water usually, but spring and fall (the best times to be camping as far as I'm concerned) are a different story.
2. I generally camp when I go hunting. Alone it's not really a major deal. But riding home 8 hours in a pickup with three others that have been hiking 15 miles a day for the past week without cleaning up is less than pleasant.
My main concern was with the pump system. How do the batteries last? Will the heater work with a water bag hung up? I have 12V when we use our camper dry, but in the tent I generally don't. For example on a canoe trip if I don't want to have to carry a bunch of batteries.
How do I like it - by FAR my #1 favorite thing about my camping/overland/glamping setup. I have gone through several revisions, this is what I have now:
I put a 15 gallon RV water tank in my Explorer where the spare tire was. That feeds into a 12v Seaflo 42 series RV pump, which has a demand switch so it only runs when the water is flowing. I put a garden hose style spigot on my rear bumper. From there, my Zodi shower hooks right up to that with a garden hose... this is where it gets complicated... I basically use the Zodi as a hot water heater, and recirculate back into the water tank, until the water is hot and then shut off the burner, and THEN I can shower. I have a small shower tent and a rubber mat that goes on the ground. I love it, my fiance loves it, there is nothing better than a nice hot shower after a day on the trail.
My one biggest complaint is that the Zodi shower isn't on demand and water MUST circulate through it while the burner is on or it'll turn to steam and blow the hoses off... thus the need to recirculate. Personally for that reason I think the Zodi sucks and I can't recommend it...and it really doesn't work well with pressurized water, there is a very delicate balance between too much pressure and cold water, and too little pressure and scalding hot water or steam. I paid $20 for it, as a recirculator, it works great, and I live with it.
I recently acquired a Camp Chef Triton 5L on demand hot water heater that I think I will be switching to eventually. The burner is on demand so it only lights when water is flowing and it only requires two D batteries for the ignitor. It will work off my existing pump perfectly, I just need a shower head and some hoses - a kitchen sink sprayer is what I use on the Zodi and it works well. Three of my friends have this exact water heater and some variation of pump setup. They all really like it and I would recommend looking at one of those. It's a fair bit bigger than my Zodi though.
Water usage - 15 gallons is enough for a day or two easily. One of my buddies has a water filter and uses creek or lake water, that's really nice if you want unlimited showers.
Batteries - my pump is wired into the battery in my Explorer. I have an AGM battery but it'll run for days and not drain it much. Don't know how it would work with a regular lead acid car battery.
If you build a shower box and want it usable with a battery besides your vehicle battery, I would highly suggest using the batteries for whatever kind of cordless tool you are using. One person I know reverse engineered a 12v Milwaukee M12 charger so that it runs off those batteries, another person uses Milwaukee M18s with a resistor to drop the voltage down to 12v. Both of those work incredibly well. You could also just buy a generic SLA battery at Interstate or whatever... or plug it into your cigarette lighter... lots of ways to do it. Cordless tool batteries are the shizz IMO.