Don't stress too much, like I said there are a ton of ways to get a glass enclosure to where you want it to be. I didn't even know PVC enclosures existed until a few months ago when I started reading about them on here. I've always used glass tanks and just modified them to fit what I need. Plus most PVC enclosures take forever to get now because of the demand. Another thing you can, the next time you do a spot cleaning of your enclosure, take everything out, and heavily spray the top of the substrate. Then just kinda of mix the substrate up so all the moisture goes to the bottom. As it dries out all that moisture will end up in your enclosure and should help as well.
The big fix for me though, which solved 95% of my problems was a humid hide. You can make them yourself or order them online. Pangea for example has one that has four sponges in the top. You soak them and pop them in and the humidity in there is 20-30% higher than the rest of the enclosure. You can make one for cheap if you don't have the funds by cutting a hole big enough for your snake in the top of a Tupperware container and then putting some damp moss in it, or paper towels if you're in a bind. A humid hide solved all my shedding issues, and while I still struggle keeping the enclosure humidity up over 50% I know that my guy has a place to go if he needs some extra moisture.
Edit: To add one more thing, make sure you have a thermostat controlling ALL of your heating elements. If you let those bulbs run non-stop with no control #1 you end up with more heat than you need and can harm your snake, and #2 the bulb constantly running is going to dry your enclosure out twice as fast.