A better way is probably to find a way to shade the RV or windows.
You could also block out the windows with something.
Try to limit the amount of RV door opening to a minimum to help keep the cooler air in the coach.
Start the AC early in the morning before the heat starts rather than trying to cool after it is already hot.
Adding a second AC unit to the roof is probably your best option.
Or upgrade from a 13,500 AC to a 15,000 AC unit.
Buy a window mount AC unit and some wood and set the unit in an open window. But don't actually use the window to support the unit, instead use a wood frame outside the window.
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2001 Suburban 4x4. 6.0L, 4.10 3/4 ton **** 2005 Jayco Jay Flight 27BH **** 1986 Coleman Columbia Popup