On a CHE/heat lamp on plex use a metal grid to keep it off the plex. Grid can be old oven racks found at Good Will for .50. I like the grid to overlap the tank. I use scrap pig panels, because I have them.

On plex you can cut an oversize hole an hot glue metal screen or mesh (hardware cloth) on the snake side (mesh is oversize so it can't be pushed out). Then put the lamp/CHE over it (using a grid).

Yes, it's overkill. But having a snake escape or plex melt is bad. Yes, I had a snake escape an learned.

Good luck!