Back in 1997, we brought our 30' 30 amp 5th wheel from Ohio where it was purchased to the Houston area of SE Texas where we were transferred. That was the most miserable experience I could imagine. This close to the Gulf Coast, humidity (latent heat) added to the temperature load (sensible heat) that the single 13.5 BTU A/C must deal with. Temperatures in the 5th wheel would follow outside temperatures degree for degree once the outside temperatures rose above about 85 degF in high humidity conditions.
We traded for a 36' 50 amp 5th wheel with 2 A/Cs in 2000 and have never even considered a 30 amp rig since. If you're planning on spending time in the South during the summers, you really don't want to repeat our 30 amp experience.
Rusty