Ok, had posted about installing the RTX2000 a/c unit (used in tractor trailer cabs mostly) into the rear bedroom of my 28' RV using the existing vent and enlarging for installation.
Well, went on a fishing trip this past weekend and temps were in the 90's during the day and only dropped to 78 overnight. First night, my volt reading started at 13.1 on digital display and ran the RTX unit on ECONOMY mode all night with 2-fans helping to circulate the cool air towards the front of the RV for my two guests. I did NOT run the normal house a/c unit at night but did during the hot days. Overall, the RTX2000 was more than cool in my bedroom and comfortable for the guys up front. Morning volt reading showed 13 volts.
Second night, I left rear a/c unit on NORMAL mode which is much more airflow. Same results overall with more cooling towards front of RV. Volt reading in morning was 12.9 volts. Overall, this addition is beyond comfortable for the bedroom area and will be too cold if all vents pointed downward ( I had the 3 air vents facing the front of the camper to push cold air forward ). It does have thermostat so can adjust the temp to your liking.
I have 3-BattleBorn 100amp lithium batteries and 800watts of solar panels up top and charging was more than sufficient for back-to-back overnight use. Prior to this trip, I used the rear a/c unit in the bedroom during the day and closed bathroom door to block off front section of the RV, and even in 90+ degrees it kept the bedroom very cold to allow for an afternoon nap. I'm sure not many Class C users will install this for a 2nd a/c source, but, it really is a great addition especially for the QUIET it provided without a generator running.