personally I'd say 79 is fine especially for a small snake they don't need as much heat. I only saw the one set of temps. That would be a yellow (zoo med?) thermometer with a white cord. Sorry I missed that.

Correct temps is the first step. I am not a huge fan of CHEs or heat lights but you have them tuned now. My preference is UTHs I feel they are easier to get right. That is a preference. Every set up and every location is different, there is no right or wrong really just set ups that are working and ones that are not working. Yours is half working.

I would try to get the humidity up some, at least in the 40% area and add a humid hide. As suggested coco coir holds tons of humidity it is cheap and looks nice and can be digested by snakes. It is my fav substrate for these reasons.

That should bring it up a fair bit you may find that it will solve thing alone but I'd guess that it would not completely but a humid hide in conjunction should be 'liveable' for you with out the need for constant mistings. I have an open top tank like yours with UTHs and I mist it once or twice a month lots of coco coir on the cool end and about 1/4 of the lid covered, with a large water bowl.

Check the accurite (salt test) I have in the past found them to be quite poor for accuracy in both temps and humidity. I am not a fan of them at all. Especially as in my area they are 22 + bucks and for that I can get 2 or 3 calibrate able hygrometers and the same thermometers.