im no full expert but if you keep it at the right temps you wont hurt it. ive had it on glass wood. fake wood plastic. never been hot enough to cause an issue
manufacturers should also be able to give you a 'flash point' on their products. Basically, it's the temperature it takes to catch fire. Anything used for housing has a very high flash point. Plastic has a melting point but even then it takes a nearly 200+ degrees to start melting cheap plastic.
If you are really worried about it you can always get some nice foam insulation (thin or thick type) and set everything on that. It's what i have done in the past and it worked great for me.
Of all the tyrannies a tyranny executed for the good of its victims may be the most oppressive. for it may be better to live under robber barons than under omnipotent moral busibodies. For a robber baron's cruelty may cease; his cupidity may at some poitn be sadiated. But those who torment us for out own good do so without ceasing because they do so with the approval of their conscience. ~C.S. Lewis