The class A we borrowed held 100 gallons of fresh water. We were in it 6 days total, but topped the water off before we left the first campsite so really 5 days...and no showers on day 5 as we "camped" in a Pilot truck stop the night before and just headed home for 5 hours on day 5. So really just 4 full days with the two of us and two small dogs.
It still had about a half tank of water when we got home, probably because we were ultra conservative with water being newbies and afraid of running out.
This coach holds 55 gallons in fresh water tank. That will require more diligent topping off and conservation but shouldn't be an issue if we pay attention.
My head goes up into the skylight above the shower when I stand in it, so I can't see me spending any extra time in there.
Get in, get clean, and get out... Plus there is only a 6 gallon water heater...that should limit the wife's shower time as well.