Never had one so can't help ther, but I thinkmthe better option would be to just make a custom plywood lid and be done with the issue. It will take longer for the polycrylic to cure than the actual making, so your not really out much time or money. Unless of course you need the mister anyway, then maybe that would be the better route.
Good post.
I've never used the product personally in the OP, but I'm sure it's capable of delivering a lot of moisture, perhaps even too much. Have you tried covering part of the top to hold in moisture?
For every 15-foot python out in the Everglades, there are thousands of species of clams, trees, cats, grasses and birds that are wrecking just as much havoc across the globe. So, for all the headaches the snakes are causing, I at least applaud them for being scary enough to get people's attention.