Heat bulbs are heat bulbs, and will dry out tanks regardless. However, I cannot say that one dries out an area less than another. I would suggest just keeping it as is, rather than spending more money.

Don't pour cups of water into your vive... they are reptiles, not amphibians that being said, I understand that misting may not seem to help much. In that case I suggest a humid hide - you can make this with just a plastic container with a hole cut in (container large enough for your snake to curl up in) and add in damp (but not wet) sphagnum moss. It is very cheap and lasts awhile. You will still need to re-dampen or change out the moss regularly though.

What type of vive do you have, by the way? Is it a glass vive with a mesh lid?

You can also try Cyrus mulch in the future as well, although I don't know if it would be any better than the coco husk. I have not used the coco husk myself.

Best of luck!