What we have done in mid August with temps in the high 90's and 75% humidity:
Turn the AC as low as you can stand in the morning to get a head start on the day's heat.
Use an oscillating tower fan in the LR.
Slip a cut-to-fit piece of Reflectix between the day/night shade and the window panes of most or all of the (single pane) windows. Nothing to see outside anyways.
Keep movements to a minimum inside to not build up body heat.
If you cook, do it outside as much as possible.
I guess 1st of all, if you can, get a site with shade. As you see in the pic, our site had very little shade and we survived with 1 AC(15K BTU).