You could use a heat mat but it would be a little tricky to install. Putting it on the outside of a plank of wood isn't practical because it won't put much heat through the wood. And putting it inside requires sealing it off with tile or glass.
I would maybe look into a different kind of enclosure. You will want something that isn't very tall since ball pythons are terrestrial. 1.5' tall is a bit excessive for a snake that will rarely leave the ground.
Another thing to consider is the size of the snake you will be putting in there. An adult would be fine, but a baby would be overwhelmed with that much space. It is best to start small and work your way up.
As for the heater, that one looks like it might dry out the air. I am not familiar with it though. A radiant heat panel might be worth looking into.