I'm sure that 7 degrees is a typo, but I'm not sure what it was supposed to read. Alex Hue definitely has a good reputation, but it still wouldn't hurt to be cautious and start out on paper. Your target should be around 80 for the cool side, though a few degree temperature drop at night time is fine and 77 is well within that, but aiming for 77 could very well get your air temp into the low 70's at night on the cool side and that's a bit too cool outside of breeding season.