Third picture is the way the shower will work at first. I'll be using the 12 volt pump I used on my old solar heat system I built back in Plano. The pump made it down here and the rest didn't. Eventually I'll convert it to gravity flow, but this will just be a quick way to set it up for now. The pump will run off my batteries and I'll have a pull chain switch in the shower to turn on the flow and turn it off. (Conserve water by soaking down, cutting it off and then turning it back on for rinsing as needed.) The pump is a low flow high pressure and only pumps about 1.5 gallons per minute, but it would still go through the 7 gallons pretty quick if it weren't used as mentioned. The flow will be through a normal shower head and should be more or less like a shower in your home when running. 50 PSI is about normal for that.
For now I've suspended working on it because it is VERY windy and sandy now. I've seen Miss Genny go in to about 30% helicopter mode several times now.
I got industries this morning and built a solar water heater out of an old trailer extension I made years ago and never used. Just more of the junk that made it down here with me (mainly for the iron. I found a better use for it for now. It is how I'll heat water for the shower. (For now)
I also piped up the shower temporarily and tested it out by running a couple of gallons of melt water through it. I've already made that up by partially draining one ice chest. Note that the temp shown in the solar water heater box it read a little over 50 degrees about 10:30 this morning. Its now 1:18 and the temp is already up to 78 degrees and I figure by 4:00 it should be more than warm enough to have a hot shower. If it were to get too hot I'd cover the box with a tarp to keep it from getting hotter. Some how I got lucky and exactly 7 jugs of water will fit in the heater. (Exactly the amount the shower needs!)