in a back heat rack typically you do not want your probe on the heattape due to this issue. i usually put my probe about 1" from the heat tape. sometimes this can be still on the back in between the 2 pieces of heat tape, but some racks youll have to put the probe on a shelf.

if you leave your probe on the heattape then you will have to up the temp while checking the temp in the tub with a heat gun.