Snake hates humidity?

My pet snake Gibdo is an eastern grey ratsnake. His humidity is supposed to be between 30-60% but my houses ambient is 20% (his tank sometimes drops to 20%) and when i mist he climbs to the highest spot in his tank, sometimes even crawling across the lip and edges of the tank lid, and sticks his face against the screen top. He used to do this before i lowered his temp from 80°f to 77°f but he'd also audibly rub his face against the screen. (He's stopped doing that ever since i changed the temps.)

If i do not spray his tank or do something interesting like feeding time or moving shit around he's chillin in his hide(s). Does he prefer lower humidity when hes not about to shed? Am i misting his tank incorrectly? I spritz the entire tank and wait a bit then check the hydrometer and act accordingly based on the number. The hydrometer is in the top corner in case that effects accuracy. Picture of the hydrometer brand for reference.

I just want him to be happy and comfortable but i dont want to give him an RI or skin issues.

I'm more than happy to receive constructive criticism about his tank setup and husbandry. Picture of setup provided (one ceramic heat emitter and a uvb light hood). His uvb is on a 12 hr timer and his dome is set to 77 during the day and 72 at night using the inkbird temp probe in the pic. The probe is down by his deeper water dish not too directly under the heat emitter. His bedding is 100% aspen shavings. All decorations are plastic store bought except the decorative real geodes.