We use our outside shower twice a year - once to make sure the pink stuff is sufficient and once when we dewinterize to make sure the pink stuff is gone. If we do have a large pot to wash, we have a double fitting on the FW hose and just use that.
In our years with the HTT and now the TT, I have only seen 1 trailer with a door on the street side. Can't recall the name, but it was right behind a slide and about 4' or so from the rear. Maybe into a bathroom?? Would like to have had a closer look, but that seemed a bit intrusive.