I'm just finishing up a 3 cage unit, but before I attach the sides, back and doors I was wondering how most people heat a wooden cage like this.

The picture is without the sides, back and doors on. Also, the sides have a 3"x6" vents on each side of the cage.

Currently I have have 2 heat pads for each of my glass cages I have the snakes in now. My idea is to stick these UTH to the under side of the wood for the bottom 2 cages. If that would work fine that what I'd like to do. The problem is I can't do that for the top cage, because if I stick a UTH to the underside of the top cage, it will be inside, on the ceiling of the cage below it.

Does anybody have any ideas for me? And will my idea for the bottom 2 enclosures work fine?