We are building 4' by 2' by 2' for our bearded dragons.....for them I am planning on hanging lights from the top. My problem is with the snake enclosures we want to build.....we are looking in to getting 2 ball pythons. I'm thinking 4' by 2' by 2' (maybe shorter we will see). But it seems like belly heat is better for snakes. How do I do this? I want to make sure it is safe. I'm thinking plywood stained and sealed. So how would it be safe to heat it? UTH or heat tape....on the inside??