What is the most stable/cost effective method of growing indoors in Palm Springs, CA?

Small area 4 x 6 temp range 70-85 degrees. Does anyone have experience with this type of region. Please Let me know
Thx,

do you ac on a regular basis?

Yes, we use AC 24/7. When we take off for a couple days temps can rise up to 85 deg when partner raises temp of thermostat to 83 deg. I have tried to convey the importance of not exceeding certin temps but it is not taken as seriously as the energy bill is each month. So every 10 days to 14 days the temps may exceed recommended for aero/dwc. What system or method should I consider that can handle 78-85 for 2-3 days without huge expense?

in a 4x6 space, a 600w hps cool tube with a good inline fan won't really raise temps too much.

What medium is most resistant to these fluctuations of temp? For instance when I plant outside White Widow and Romulan grow pretty well. The temps reach well over 103 deg during peak of summer. I know this is not optimal but it seems that the sandy soils keep root systems cool enough to transpire water and nutient. Then fall sets in and its much more moderate with cooler nights. So outside is one option but inside I have more problems with bacteria and bugs. Is desert sand a medium that can be used if so how do I prepare it for use in an ebb and flow?

If you intend on running those hydro I would suggest 600s with good inline fans, and a chiller for your res, or switching it up to soil to control the root temp better. I will be back in the DHS/PS area in June and firing up four 600s! I always ran a chiller on my res and used a much larger one as well. But in my latest days I have found soil to be much more reliable and stable in the desert(been doing it along time in the desert).

I have found growing in organic dirt to be very cost effective and low maintenance. Plants handle temps from 65 to 98 and still gave good yield. You also get more from your water resources.