If your concerned with the 120F temperatures I assume you are planing on growing outside. I am not sure what your winter time temps get, but here it gets into the 30'sF. I don't think you will have much luck with tomato's in and around those temps. The cold was too much for mine (along with another problem). I had a plan to cover them and heat the inside at night, but I never had the money to complete it. You may be able to find cold tolerant variety's, but tomato's mostly like and do better in warm weather.
Cooling in the summertime is and can be expensive, that's why I like the idea of using "geothermal energy" (free energy) to cool the
nutrient solutions. I didn't really have that option last summer. I recently built a geothermal reservoir for my tomatoes that only cost me $30-$35 for a 20 gallon reservoir. I plan on building the same one for my melons.