Wooden Caging- Questions and Concerns

[Trisnake]

Hey guys.

So I was browsing my local Craigslist and I found a guy selling some enclosures he had built a couple years back. They're wooden, with a front-opening swing down door with locking mechanisms, inside lined with tile and (from the photos) sealed with what I assume is some sort of aquarium safe silicon or epoxy. Two small mesh air vents on either side of the enclosure for air flow, and the cages are stackable. 4'x2'x1' dimensions, FOUR of these guys for 300. Heating already installed.

My only reason for not absolutely pouncing on these enclosures is the way he heats them. Because of the thickness of the wood he had used to build the enclosures, he has the heat pads installed INSIDE the tank. This is worrisome to me as everything I have ever read (as well as what common sense tells me) is that the heating pads are absolutely NOT supposed to be inside the tank, as the snake can come into direct contact with the heat pad (possibility for burns) and because the pad can get wet and malfunction/electrocute the animal. When I asked about this, he outlined his system as putting the pad in the cage, thermostat probe underneath, then adding several layers of newspaper on top of the pad, with a cut piece Astro Turf topping it off. Despite the fact that he has "housed animals in these enclosures for 6 years like this with no problems yet", it still worries me.

My question is, is there a way to make these enclosures work in a way that is not an absolutely massive effort on my part yet is still safe for my snakes?

I've seen people with wooden vivs like this put the pad on the inside, and then put a piece of slate tile over top of it so the animal doesn't come into contact with the pad itself. Anyone think this would work? I would of course seal the tile down with aquarium safe silicon so that no moisture can leak under to the heat pad.

All insight is appreciated I'm just hoping I can find a way to make these cages work, I really like the price and they look like nice, well made enclosures.

edit: and no, these won't be for ball pythons