Totally agree and experienced the same results with that day/night temp.  Use to think my tent was in the low 80s in the day, but then hung my thermometer at the canopy and it was high 80s almost 90.  Bit the bullet and finally turned on the wall unit that i had installed in the grow room for controlling the temp in the first place and viola. Got the temps down to 79 during the day and like 68-9 at night. The best grow I ever had, straight up fire, the buds were super dense, like I use to think those people that had those moon rock buds were using a press, na, they just got their environment dialed in.  Waiting on this next run to see if the temp thing holds true.  I'll know because the strain I am running I have run with whacked temps.  I ran some auto's and they hermed, now i'm thinking it was because of the temps for sure, I know I don't have light leaks.  So yea take care with temps on auto's, at least from my limited experience.  Good luck and stay lifted.