As others have said, trying to cool down that rig with 1 A/C unit is a lot to ask. My old Allegro 31-footer has 2 A/Cs but only one runs on the 30 amp shore power. The one A/C that runs off of shore power is up front in a lounge area. It will suffice most of the time. If it starts to fall behind I close off the partitions to the rear bedroom and cab. It will then catch right up. At night I open the partitions back up and let it cool the bedroom as well. Absolute worst case scenario is I can fire up the generator to run both A/C units. If you're willing to spend the $$ for a 15K unit, I'd keep your 13.5K unit and install a second one. Doubling the cooling obviously makes a huge difference.
