I did fine with one 13500 in the Jayco living in it here for a few summers before we bought the house and up until I sold it.
I kept it cool and the unit cycled on and off throughout the day.
If you have two you should be fine. I did keep the blinds shut during the heat of the day which was a big help.
With the humidity here the key is keep the door closed, before it can cool it has to draw the moisture out. I was less than 15 miles to the open ocean both at the campground and here at the house. At the campground I was under some big live oaks that provided shade, at the house here it was in the open with some shading later in the afternoon, never a problem staying cool.
We did use it for a few years at the house for guests to stay in until we decided to sell it and get something smaller that we have still yet to find.
Never a problem keeping it cool here either.
Chris & Dianne
Jayco Designer 3110 SOLD 6-11-2016, looking for the next one.
F250 PSD 4x4 Crew Cab