I had the same issue with humidity. I have been told by multiple sources several of which I consider reliable that the high humidity of say 85 is not bad. As long as there is no condensation I was told that I neednt worry.
I use aspen and it took a bit for the residual moisture it had to dry out. My humidty right now is at 73. My snake is in shed. It never goes below 60 unless I keep the ceiling fan on constantly in my snake room.
Someone posted on this board about the conditions in the termite mounds where these snakes live and the humidity is in the 80's range. Of course I am going by memory.