Mounted it up yesterday, along with 2 interior LED fixtures and switched the 2 bulbs in the ceiling lights to LED's as well. I'll post up pics when I get some free time. Went smoothly.
To answer the questions, it's a 1978 Grandby. Not much in the way of existing wiring. Just one set to the heater, which has been replaced, another to the lights on the ceiling. I've wired everything else myself, including the 85w solar setup. Running a bluetop Optima. While I've never had power issues, it's nice to reduce draw. Once it gets really cold, I expect to be pushing the limits of the panel and battery.
Edit for pics from yesterday:
1) The exterior scene setting up for camping. I've got a speaker mounted that pivots to face outside so I can hear tunes.
2) Where I chose to mount the light.