We need reliable cellular data, so an omni-directional and rotatable Yagi antenna on a mast will be implemented. A cellular repeater/amplifier will feed the signal from the roof to a directional antenna inside the RV.
The RV will have its own wifi via an on-board cellular modem capable of multiple carriers.
A simple website will be hosted from the RV wifi with a Pi 3, and from that site, some home automation software will be exposed.
Add physical interfaces via relay boards to the slide switches and nearby lights. Leave the existing switches in place for the lights, but have them trigger the automation software instead. This will essentially turn them into 3 way switches with the hidden switch controlled by the automation software. If the switches are already 3 way capable, then wire them as such. The relays are SPDT so this will work, and this way everything would still work even if the automation was off.
Tap into the analog signals feeding the black, grey, and fresh water tanks.
Add an RS-485 interface and tap into the communication between the wall panel and the house inverter to get battery and line status. Later, perhaps actually spoof traffic and trigger things like starting the generator via the AGS system.
Control over the AV systems would be nice as well, and the RV came pre-wired with an HDMI over ethernet 4x4 multiplexer. I'll need to emit IR to control it and the other home entertainment stuff.
Figure out where to put a projector and screen as we need the space currently occupied by the living area flat screen for other stuff. I'm partial to using the front power window shade as the projector screen currently with a short throw projector hidden either in the dash or in the upper cabinets.
Lastly, integrate with Alexa, Google Home, or CMUSpinx for voice control over the simple stuff.
This is going to be fun. :)