||If you live on the east coast use PowerTech-they are in Leesburg, Fla. If you live on the west coast use Wrico. The only reason I didn't use Wrico, is that I didn't know of him until later after buying my PowerTech. I chose the PowerTech because it uses a brushless alternator with a simple voltage regulator, simple high water low oil sensers that trip universal Bosch relays, all other relays are the universal Bosch-all easily obtainable from an auto parts store. Wrico makes an excellent unit and Dick Wright (owner) is absolutely the best for information and installation knowledge. If I bought again, it would be a Wrico with electronic controls so I can interface with the new smart inverters. Some of the new features on the inverters is automatic gen start if the batts get low, kicking in to help the load when on the power pole if you draw more than the power pole can provide, etc.
As far as A/C's, I have 3-13,500 Colemans with the front one close to the front since I don't have dash air. I only need to run the three if it is over 100 out. Usually run the two outers during the day and the center one at night. They are the old fashion type that are not ducted. Personally like non-ducted, seems to get more air blowing. Coleman is good, but only has a two speed fan that makes for a bit noisy night time use. I would use the Duotherm Penquin since it is low profile and has that third speed for quiet night time use. I don't know about the Carrier, other than I know it is a good unit. Even though roof tops are ugly and make for higher up weight, they are cheap and easy to replace if one craps out. But in the 11 years I've had them, not one thing has gone wrong with them. Good Luck, TomC