Want to replace shower with shower/sauna/deep tub...

I've been on the road for 12 years now I stopped moving the last two. I may or may not travel again. I'd like to use a portable hot water unit (something that heats the water as it flows out of the hose) to create thigh-high tub for one in the footprint of my current shower --or-- a sauna shower combo...or maybe all three.

Any thoughts? Weight would be an issue. Is there any way to build it with wood? wood? Maybe remove the base entirely and build a rectangular shower/sauna in its place? Or keep the base only and build a wood surround for the outer walls? Maybe I could lighten the load enough to compensate. My rig has space for a washer which I don't have and that's pretty heavy. ?

Gonna make this happen. At the very least I need either a soaking tub or a sauna. If I had to choose I think I'd choose the former over the latter. And that would probably be the most lightweight option. How do I add a portable water heater and would I remove my old one? Where would it go? Inside or outside? No idea. It's chilly on the Oregon Coast in the winter and I'm determined to build it...has anyone ever tackled anything similar?

My current shower is a corner unit with three sides. I think I'd like to remove that and make it rectangular. Or have the existing glass cut to accommodate a tub base which is higher than the existing base. I'm completely removed my shower before and replaced it with different glass so that's not a problem. Best case is a Japanese style deepish tub (I'm 5'7" 120) with a wooden surround. Could be large glass sections on top but I'd like the supports to be wooden also. What kind of wood/treatment can survive the water?

>Thanks much...