Just to update this, we're doing a custom steal shower pan behind the driver. Will be about 30x15. It'll be powder coated black and our shower curtain will be in a rail in the ceiling. The curtain will be parked and velcro'd to the wall behind the driver. We'll then have several rows of L-track (two above the window, two below the window).

Essentially, this shower will serve as our bathroom (curve porta potty - pull the curtain around 3/4 to have privacy), vertical ski storage in the winter, wet gear storage, and we'll use the L-track to do vertical bike storage in the summer. Mostly, we'll use a hitch rack, but it'll be nice to store them inside for certain trips. We're fine take a few minutes to move the porta potty into the hall way to shower, or any other gear in there. This way, the shower doesn't take up any additional room, and also serves as an area for wet gear to drip into.

I can easily shower with 1.5 gallons of water. We've been using wipes all our outdoor life, and it just doesn't cut it when you've been sweating profusely all day and want to have sexy time at night