I was hoping someone with more meaningful experience would chime in by now but let me take a stab at it. First of all, I grow my Sarrs in the NE US, not the SE, so have more insight regarding winter, not summer extremes. But I lived in Mississippi for several years growing up and also in college so am familiar with the climate/habitat.
I don't think those temperatures are good for the plants but hopefully they weren't immediately fatal. What I think you should try, if you can, is to dig a hole the shape of that bog so the lowest several inches of the bog are in contact with soil. Ideally, the soil would be at least as high on the outside as the water is on the inside. Higher is better, but not too high. You don't want surface water and debris flowing in and you'll want to be able to dump the water out and replace it occasionally - I like to do it at least once or twice a week because of mosquitos. If the soil or property owner or the parents make that too difficult, try mounding mulch around the outside of the bog, but not so high it can wash in.
By the way, these steps are similar to how I get Sarrs through the winter. The only differences are that I take the pots out of water and put them in the ground to within ~1" of the top of the pot and then cover the pots with 6"+ of dried leaves and long grasses. They survive temperature of -10F that way. You don't want mulch on top of the plants during the growing season, of course, but good ground contact and judicious use of mulch is a great way to moderate temperature swings.