If you are worried that isn't enough light and want to stay with a single 250 watt halide consider getting a 36" PFO parallel reflector. You can put a sinlge metal halide in the center or one at each end of the reflector.
With a single reflector in the middle you will get enough light spread for the entire tank.
I have this reflector with two halides, one at each end of the reflector, I can cut just one bulb on and it lights up enough of my 36x18x15 tank to keep SPS anywhere IMO.
I use two to saturate the entire tank with light and hopefully prevent bleaching or recession at the base of my corals as they start growing.
I know what you mean about the heat, it gets bad out here during the summer too, and we typically deal with a very high humidity. we don't have to deal with 105+ though.
Here is a picture from our last local reef club meeting. Part of the guys tank is out in th garage with a chiller. The high temp is the outside air temp, the lower temp is his chiller doing a dern good job:
http://www2.freepichosting.com/Images/421522708/1.jpg