Sooo, this total setup worked great for us during our time in Acadia National Park for 3 females and 1 male...
1-Zodi Outback Gear Shower $129...
https://www.walmart.com/ip/Zodi-Outback-Gear-Zip-Shower-with-Piezo-Soft-Case/26968298
1-Ozark Trail Shower Instant Shower Tent for $116 (or $65 for Non-instant)...
https://www.walmart.com/ip/Ozark-Trail-2-Room-Instant-Shower-Utility-Shelter/42391766
1-Soft Cooler for $26 similar to this...
https://www.amazon.com/Coleman-C006-Soft-Collapsible-Cooler/dp/B00LGVT9EK
What we like about this setup is the Ozark Trail Shower tent has 2 rooms; 1 for dressing/undressing and 1 to shower. The rooms have a divider so the dressing/undressing room can be kept dry. Of course, the dressing/undressing room can also act as a toilet room.
In the shower room I place the Zodi and the soft cooler. I fill the soft cooler with approx. 2 gallons of water, drop the Zodi water pump into the cooler and also drop the showerhead into the water-filled cooler. I turn on the Zodi and the water pump and let the water cycle through the Zodi until the water has reached the appropriate water temperature. The shower tent has zippered windows and an air-gap near the feet so there's plenty of ventilation available.
Once the water reached the desired temp I turn off the Zodi and water pump. I also just leave the water pump and showerhead in the water and close the cooler lid to maintain temperature. For young and adult, I just tell them to not touch the Zodi, turn on the water pump, and wet themselves down using the showerhead. Each time they need both hands they can just drop the showerhead back into the water-filled cooler. I tell them to lather up then rinse off. After rinsing off they just need turn off the pump and close the cooler lid to conserve the water's heat.
The shower tent's zip up windows, when zipped, help retain heat on cool days so it's very comfortable keeping warm. It's also okay to run the Zodi heat exchanger while showering but I think that's best only for adults who understand the risks (as opposed to kids). During the summer heat retention isn't as important so we're using an empty grain bucket like this,
https://www.walmart.com/ip/Augason-...Emergency-Food-Storage-26-Pound-Pail/22001478, and in either case, the Zodi fits inside both container.
If I had to change one thing it'd be the soft cooler. The bottom can get saturated so either I need to spend more money on another cooler with a water-retardent bottom material or build a platform on which the cooler will sit.
Showering is critical for me because of I have severe skin issues. We have the Helio tank but it ended up being inconsistent in temperature and pressure. I also looked at the Helio shower tent but the Ozark Trail shower tent, with 5-stars, is hard to argue against. And $500 for the 10-gallon pressurized tank was a non-starter for me because I knew I could build something close to its functionality for a fraction and it wasn't as portable. That's not to say they're not quality products but I couldn't justify paying multiple times more than my setup that's lasted several trips with kind care with no issues.