I suppose it's time for a couple updates, eh?
I've been working lately on the sh*#ter/shower. It's coming right along. Here are some pics:
That was a picture of the shower pan to be. I purchased a 2" thick, 30psi, 2'x8' piece of foam board (Foamular C300 in this case) for the shower pan. It's not quite as dense as a Kerdi foam shower pan, which is 48psi, but it should work for such a small area with the amount of traffic it will receive. Also, the foam board I purchased is several hundred dollars cheaper than a Kerdi shower pan. Normal foam board is 20psi, by the way.
I used an old school automotive battery charger and a strand of thin, stainless steel cable to cut a conical shape into the foam. The bolt that the negative terminal is attached to is where the drain is going. It all slopes inward to that point. It looks messy, but after sanding down the ridges it looked much better.
I cut another piece of foam board the same size as the pan, glued it down, then glued the shower pan to that. Should be plenty of insulation for those cold, wet feet.
In this picture the pan is in place and glued down with plenty of PL Premium. I filled a 50 gallon bucket with water to put some weight on it and make sure it wasn't going to do anything funny while the glue set.
Yup, looks pretty rough right now. I was working on the backsplash for the sawdust toilet. Once the polyurethane dries I'll put it together and post a picture.
The shower pan dried so I moved ahead with installing the drain. It's glued in with PL Premium as well. You may be thinking, "What a fool! PL won't adhere to ABS!" and you wouldn't be wrong. However, I read a neat trick where you first lather the ABS up with proper ABS cement then, while it's wet, apply the PL Premium. We'll see how it works. The drain is held down tightly by a 2x4 wedged against the ceiling. I'll be doing the entire room in FRP, so I'm not worried about scuffing up the ceiling.
Wondering why I haven't used thin-set mortar and all the other standard shower installation techniques? Because I don't trust it in a moving vehicle, that's why. I'd expect it to start cracking in no time. I like the slightly flexible stuff best. It's my bus, I'll do what I want!