I have thought about this in our 69, but will keep the bath for now as we have 2 small children.
I am gonna have to redo the whole thing anyway, and am going to use the plastic 1/8 4x8 sheets of wall cover you get at home Depot. You could construct one yourself out of this. It would be the floor pan that would be hard. I would try to fine one that is pre fabbed.
May you have at least one sunny day, and a soft chair to sit in..
2008 5.7 L V8 Sequoia
AIR # 31243
WBCCI # 6987
FOUR CORNERS UNIT