Buster.....
Down here in Texas it gets pretty hot (above 100) and the humidity is pretty rough also.
My wife sewed two nice looking shower curtains (coach décor compatible) together (to make them floor height) and I put a nice looking wood rod across the width of the coach (just behind the driver's and passenger's chairs). The whole installation looks very nice. With the shower curtains pulled together (it closes off the front totally)the front dash air keeps everything very comfortable. The part of the coach behind the shower curtains get very warm so I turn on all three air conditioners for about 15 minutes before we stop for lunch to let the back cool down a bit.
Works for us.