Some things I have heard of: mistreat your plants, as in prune, don't baby with water, no verbal abuse, however.

Eggshells, magnesium sulfate (yes, the bath salts kind, no fragrance, get it at the dollar store)

Keep them evenly watered and mulch heavily to retain soil moisture. Use soil sulfur to free up the soil iron, fertilize lightly if at all.

Punta Banda should have done well, most "heirlooms" can't handle the heat here and produce badly. Look for hot. "Matt's Wild Cherry", a tiny cluster tomato, does really well for salads.

Growing ultra-short seasons tomatoes to get a crop in before it gets hot is another tactic. Use the ones meant for Siberia and Canada, but plant them out as early as you can. Then do another batch in late summer for fall harvest.

Lazy's points are on target but I especially like the last paragraph. We often have mild winters and can grow a good crop at that time. Successfully growing tomatoes here in summer is almost impossible. Although gardener Leslie Doyle in Las Vegas pushes the Hawaiian Tropic tomato, promising it will grow in the heat. That tomato has mixed reviews as to flavor. I'm trying it this year to see: a) will it really grow in summer and b) how does it taste? I had serious germination issues with the seed I purchased from her, only got 4 seedlings from 8 or 10 seeds so that's disappointing to begin with!! But growing to production only to have bland tomatoes is just as disappointing as losing the tomatoes to heat stroke.

I planted 5 or 6 tomato seedlings of different varieties in Sep last year and have been harvesting tomatoes since early January. Once that one week of frost temps passed, they started producing. I had to cover them and provide lights for warmth under the cover for the frost time, about a week I think. The plants have slacked off a bit lately but I just pruned back all the dead branches, poured on some fish emulsion and expect they will get a new spurt of growth and production before the heat heats.

I have grown Super Sioux in the past and it did well in the heat and is very tasty, a large slicing tom. Another good one for here is Silvery Fir Tree, a 'salad slicing' size (I don't like currant size toms, WAY too small). I learned about this tomato from Gregory Ware who teaches various gardening and cooking classes through Southwest Gardener, which is how I met him, a "How to Grow Tomatoes in the Desert" class. He's very good. You might want to try one of the classes. SW Gardener is an eclectic gardening supply store in central Phx, 15th Ave and Thomas I think. Here's a link: SW Gardener Workshop Calendar

Just keep trying till something works!!

off topic from Native Seeds/Search:

Flamenco

An excellent open-pollinated tomato for the Southwest.
Flamenco is a cross between Silvery Fir Tree for earliness and feathery
foliage and Floridade for heat and disease resistance. The result is a
semi-determinate 4' bush loaded with highly flavored 2", red round
fruits. Nice acid/sweet balance and great flavor. Continues to produce
in hot weather when others stop. Performed very well in our 2012 trials
in both Tucson and Patagonia, Arizona. A staff favorite! Approx. 0.1g/25
seeds per packet.

Thanks Grubby. I tried Floridade once but it didn't stick with me so I guess I was not impressed. I'l try Flamenco.....just ordered!