That's what my post was for:
To generate interesting thought(and to maybe get some added information from those who changed to tanked from tankless. I already have plans for the tankless in case I'm convinced to change to tanked. I convince easily and do mods for fun. )
The above link is the ro unit I have in my home.
It has a built in pump.
I don't have an ro in the rv. 16oz Bottled water is too easy.
The ro can allow close to 100% water savings from the rv shower and sink. You can run ro expelled water right back through an ro.
Run the expelled water through a Brita for drinking.
I try to post alternatives as a service to newbs and people uncomfortable with thinking beyond what's initially presented.