I'd lower the heat mat to about 85*...she's an "albino" black rat snake, & while they like humidity, too much can cause issues too & they're adaptable anyway.
(what % of the floor does the heat mat occupy? is it at one end or in the middle?) A better way to offer humidity is a humid hide...use a large enough plastic
food container (lid on) & cut (or melt) a doorway in the top, fill with damp (fully soaked & drained sphagnum moss) & refresh periodically to keep it damp.
Yes, your heater blowing on the cage sounds like a REAL issue. Always have to be sure of cage placement with regard to heat, A/C vents and windows that sun
can stream in thru- avoid all those! All cages should be in a stable area, well away from all that & away from doors that open to the outside also (for drafts).
Snakes "burrow" when their hides are too tall & too open...easy fix: crumple a paper towel or two & stuff them inside! You'll find your snake in there, happy.
Or you could probably give her a Christmas stocking...(an old un-matched sock works too)
And rather than misting, a larger water bowl will add humidity, especially if it's near the UTH.