So, what do you expect from your rig AC? We have a 13k BTU AC in the front/master and a 15k BTU in the living. At present, the main 15k AC is keeping the rig at 10-12 degrees lower than the outside...
We have 2 15K BTU ducted Dometics in our rig and can hold 73 degrees inside on a 100 degree day. A lot has to do with the insulation properties of your rig (I would have thought a Cameo would be pretty decent), shade, etc. Our rig also has double pane insulated windows and MCD sun shades on the windows. I certainly would expect more than 10 to 12 degrees below ambient.