Unfortunately, no good solution
I agree that the insulation is not anywhere near what you would expect in a house, so you only have two options: increase the insulation somehow or increase your a/c power or both.
We are currently in Yuma AZ with two 13500 btu units on our 31 FE. Today was 116 degrees F, and we got up to about 76 degrees inside and tomorrow is supposed to be 121 degrees F. I'm curious to see how this works, but I suspect it will be about 80 degrees or so inside, which is acceptable in 10% humidity. We will be adding some blankets over the windows to keep as much heat out as possible, and we do have some shade in the late afternoon.
wsgts
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