We have awnings over each window plus the patio awning. All windows have mini-blinds and the windows are lightly tinted.
When it's over 100 outside we can keep our 364 square feet at 80 or lower with one Dometic 15,000 btu unit.
Here's what we do-
> Once the outside temp reaches 70 or higher we turn on the A/C and set the thermostat at 57. I have found that if we turn it all the way down the A/C doesn't keep the trailer as cool (weird).
> If the outside temps will stay above 65 even at night then we leave the A/C on 24/7. This keeps everything in the RV cool (walls, counters, furniture...etc) so there is less radiant heat for the A/C to overcome.
> If we get cold we put on a jacket or use a blanket.
> The goal is to keep the RV as cool as possible without the typical adjust the thermostat up or down for comfort.
> All of the awnings are deployed and the mini-blinds are turned so the sun is blocked from shining in the trailer.
> The entry door stays closed as much as possible once the outside temp reaches 78
> We keep the ceiling fan on to help circulate the air and use portable fans to direct cool air into a couple of areas that are hotter than others like the rear corner dining area of the main slideout.