i drill out the rivets, tap, and bolt the baffles back in. that way i can get any residual grime and caked oil from inside the cover. i also do a pcv reroute. and since the driver side exhaust baffle is plugged due to reroute, i leave that baffle off. maybe i am just going above and beyond.....
but to answer your question, they will not melt unless they are touching the metal rack.