I too will be adding a second AC unit to the Octane TH specified in my signature section below. I contacted my local dealer and asked if the second AC unit would be duct-ed and they said no. They claim it would be non-duct-ed and therefore not operated via the wall t-stat. My TH TT is different than yours in that the main bedroom is up front and the single duct-ed AC unit is a pretty good distance from the bedroom. I do have the 50 amp upgrade however, I plan installing an 11K BTU Super Saver Coleman unit because that will afford the ability to run a single Yamaha 2000 gen. with no problem while boondocking as long as I'm sure sure to disconnect the main inverter so the battery charger won't create an overload and also switching the fridge to propane. I elected not to go with an on board gen. and will be pairing two 2000 watt Yamahas to run the main 13.5 AC and other stuff during the day (not both ACs together, however) when boondocking. Of course, if we are at a 50 amp CG hook-up, I could then safely run both ACs and most other items because I am set up with the 50 amp Progressive surge protector first from the pole, 50 amp Hugh's autoformer second followed by a Sure Guard multi-phase protector. Based on what I learned here on this venue, I should be good to go for most power needs.
I will most likely later get into a decent solar system as well as upgrade the brakes to the Kodiak 7K disc brake system to go with the 17.5" tires and wheel upgrade. Sorta, kinda seems like these upgrades are and will be endless and expensive but, if one is going to be in it for the long haul, it is what it is, eh?