I live in Florida and the only time I use a dehumidifier is during the cool months when it is too cool for the AC and not quite cool enough for heat. A properly sized AC unit will remove more moisture and not add heat to the area. A dehumidifier will only lower the humidity somewhat and, in the best case scenario, will not lower the temperature.
You need to run the AC unit as much as it takes to keep you comfortable. The humidity down here can be around 80%+ and just opening one door will allow a bunch of moist air in to your coach.
Run your AC and maybe a fan or two to move the air inside the coach. With air movement you can keep the temperature a little warmer.