Your hot spot doesnt have to be 90, solid numbers shouldn't be thrown around..from my knowledge and from friends experience,some BPs prefer it cooler...if my side gets up to 90-92 my snake finds his way to the cool side...but I keep the temp of the tank around 86-88 warm side and his hot spot in his hide about 85 and he is very comfortable..very hungry always.
best of luck,hope this is helpful
id focus on a warm side of atleast 84-90 air temp and in his hide the heat pad to be set around 82-86 and see how he likes it..