Hey Sage,
I just started this very process.. Just tore out my old carpeting, Fridge and heater. I have a '83 Mini but my layout was similar to Debbits, I hated the placement of that fridge crammed in the rear with the stove so it had to go. I had 3 gas lines and a 120v outlet back there so I plan reroute the gas under the cab and tie in a Interior and exterior rear light with that 120v line. My fridge had to come out the window as it didnt fit out the door. I LOVE how much space I have now it is like a whole new Mini to me and I just more and more of a blank canvas. For me Bumper mounted coolers work just fine and once I get a nice inverter and battery set up Ill move on to a electric cooler but those old 3 way fridges take up alot of room.. and in a RV where every SQ IN counts Ill take it.