Looks to me like you need more hides/ cover in the tank. Go to the dollar tree (if you have those in your area) and buy some fake foliage. Those can be a nice way to add coverage in your tank and also help your snake feel more secure. The cool side needs a hide.

One thing you could do to increase at least an area of humidity that will be a little longer term than just spraying is add a humid hide. I don't have as much experience with Balls. I've done this for my Corn Snakes if they are having issues shedding. It makes sense to me though that you could add one of these for your BP for while you're gone. They also are pretty cheap and easy to make.

Take a Tupperware container, old plastic container from yogurt or something, ect. Cut a small hole in the container.. large enough for your snake to enter and exit, but not too large. Get a bag of sphagnum moss. This will be the most expensive part of the project unless you want a really fancy looking hide. Soak the moss in warm water. stuff the container full of it. I'd keep it on the warm side of the tank so that it ups humidity even more. You could always rearrange stuff a little and put the large hide you have in your tank on the cool side, and switch a humid hide and the water bowl to the warm side to up humidity.

Here is a visual example (not my picture) of a humid hide.