Today I finished touching up around the water heater opening. I had also filled the rub rails with Great Stuff Gap Filler foam at the end where it has been cut. After it dried I cut the foam flush, sanded and painted it white to match the rub rail.
Next, I screwed the RV-500 water heater in place and put silicone all around it. Then I mounted the door. The exterior is done! (The blue tape in the pic below is the pilot hole for the side fridge vent/access door.)
On the inside I hooked up the appropriate gas line and attached it to the main 1/2" line.
I wired in the 12V and ground wire also.
All that need to be done is the water lines.