Hi there STTT,
Thin and/or shorten the branches on which you want to restrict growth and favor the ones that you do wan to grow by letting them be longer and more dense.
If you find a way to shade the tree's pot from the sun, it will go a long way toward helping it survive the summer season. *The problem is typically, that the pot heats up and cooks the roots, and once the temperature in the pot rises above a certain point, the tree can't move water.
So you could try shading the pot (or the entire tree) at that time of year. *Some go so far as to wrap the exterior of the pots in aluminum foil, but I think a little shade cloth would be a better idea.
You will also see mist kits appear on this forum below from ***CHARLEY*** on this forum, which can reduce the temperature, but evaporative cooling is only effective when the humidity is low, so if you get heat & humidity where you are, pretty much all you can do is block the sun.
Please also take a look in
bonsaiTALK Links and search on ARIZONA as some of the club members there have similar issues.
Good luck,
Matt