I use a mix of sterlite tubs Animal plastics enclosures/Racks a couple home made enclosures. I have almost totaly switched over to flex watt now as my heathing methode (much cheaper than UTHs).
The UTHs that stick to the glass will almost always tear up when removed from the glass, and they say not to use them with plastic but I do/Have and have never had a problem. The way I look at it is, if it gets that hot to melt plastic think of what it will do to my snake.