I used choroplast pieces cut to size to fill in the gaps and no snakes ever got out.

The heat does not warp the plastic.
You have to remember, the heat needed is cooler than body temperature...

That being said...

They do not hold in humidity very well.
Even with no big openings, there are still many small ones and all at the top. Heat and humidity both end up escaping.

I pulled mine apart and turned it back into a storage rack for all of my supplies.

-Steven