Sounds like a hard find as it would take up allot of space but a cool idea. Best part you wont have to wear crocks in the shower or have to worry about the nasty shower floors.
All true. But it is also true that if you don't keep the truck shower floor clean, it will become nasty.
Diane and I have a shower in our truck sleeper but seldom use it. We would include it again if we built another truck because it is fantastic to have when you need a shower and one is not readily available outside of renting a hotel room. The freight or freight schedule sometimes takes us where showers are not redily available and in those times, the truck shower is wonderful.
The down side is simple. The more you use it, the more you have to clean and dry it when done, and find a place to refill your water supply. You also supply your own towels and wash clothes.
Think about how it would be to use truck stop showers if you had to supply your own towels and wash cloths, were limited to using no more than 20 gallons of water (each for team members), before you could shower again, and had to clean and wipe down and totally dry the shower (so the sleeper does not smell musty) after every use.
A shower in the truck is very nice to have but it is not without costs in time and effort when used.