Thanks all! Great info. I'll watch some of the videos to see if I want to tackle this and I'll get a quote from the shop to see what that looks like as well.
To answer a few points above, yes the wiring is there. There is a plate in the ceiling right next to the vent that has a sticker saying AC wiring located here etc etc.
One final question- Noise... Is there a particular brand or model known to be much quieter than others? Our main unit is Dometic and the noise level is fine. It is better than our last camper but also 15 years newer. That said, being right over the bed I would prefer something even a bit quieter if such a thing exists. Let me know if you have found a super quiet Non-Ducted AC unit, and do the "low profile" versions work quieter?? Thanks!