If the room is going to get that hot anyway, then you definitely want to turn off the hot spot (but I think I understand that you're debating whether to run the AC and hot spot, or neither). As far as signs, I'd watch for changes in feeding habits (suddenly going off and staying off), soaking excessively, and restless activity during the day when they are usually sleeping - pretty much the usual signs when anything is stressing them. Oh, and to your first post, I wouldn't let it get all the way up to 88+, because then it's like they are living on one big hot spot. ~85 is too warm for a "cool" side, and too cool for a "hot" side.