i'm assuming you're out in the desert with those high temperatures. you definitely don't want the water temperature to get anywhere near 100 -- most fish will poach well before that, and water holds much less oxygen when hot than it does at room temperature. shade the tubs for at least the hottest part of the day, either by location in your yard or with a screen (sunshade material from the nursery). you could probably drape it over the tub in a tent-like shape as long as you aren't restricting air flow.
altho your daytime air temperature is going to be a problem for many plants, floating plants / leaves to cover the surface will be pretty much mandatory to help keep the temperatures down, and will help with the oxygen problem; at the very least, get some good floating and submerged oxygenators. check with a local pond or garden store to see what works in your area. also, if you live in CA like i do, a lot of the better warm-weather floating plants (e.g. hyacinths) are restricted; this is true for a number of other states (e.g. FLA), so check your local rules.
see
http://www.aquariacentral.com/forum...Are-the-plants-you-re-selling-trading-ILLEGAL
if you have rooted plants, repot them in a non-fertilized medium such as sand + sphagnum moss or coconut coir; the normal fertilization level in potting soils will cause a huge algae bloom, which will knock the night-time oxygen levels down.
if the water (not the air) temp starts getting over 80 you should definitely have an airstone going to keep the oxygen level up. i have never had that problem -- my tub has been running for a few years now with no filters or airstones, only topping off for evaporation and dog-drinking losses -- but i have much cooler summers.
you should also shade the sides of the tubs or paint them white to reduce the heat load from that direction.
in any case, expect to do a lot of topping off to account for evaporation; my small (~10 gallons of water) tub in mostly full sun loses about 1/2" of water a day during the summer, and we normally don't get much over 80 here.
don't put in mosquito fish if you want to have ANY other kind of fish with them; they will harass anything smaller than 12 inches long
if you need to either cover your bottom grate to keep the fish out, or make your own "pots" (more like burlap bags) for rooted plants, you can get weed barrier (basically very fine black plastic non-woven cloth) by the yard at most nurseries, and probably at Home Depot or Lowes.