For starters I keep the ceiling fan on in the snake room for mild ventilation.
If I remember, you have AP cages, as do I.
If humidity gets too high, I go into the snake room several times a day and open the doors to the cage/s and point an industrial type fan directly towards one side of the cage at a 45 degree angle and the air escapes out the other end taking humidity with it. I do this for 5-10 minutes or until a snakes tries to escape. This does a rapid quick fix, but the high humidity can bounce back within an hour or two. But repeating this will eventually bring it down to a stable %.
If things are way out of hand with water on the windows and sides, then I barely open the doors on each side of the cages about **1/4 inch.(after doing above step) I check frequently to make sure no one is trying a prison break. Usually within 24 hrs humidity will drop to the 70 ish range. You can do this with or without the fan running.
** only leave the doors agape if they are glass! I’ve had my big Carpets and Boas bend the thick plastic doors permanently and escape. They have also blown the doors out AND the tracks out due to the spring action of the plastic. So this potential may be worse with your Burm.
Other than these tips, you could install adjustable vents.