If you get the caulk anywhere that is visible when the light is put back together, don't use goof off to take it off, it will eat away at the lens. I have an extra light sitting in my closet right now because there is an opaque spot from the goof off eating the plastic away on the lens. Not sure what I'm gonna do with the light, experiment or something.
When I did mine I used two layers of cardboard underneath, and a layer of tin foil between, just because it was in the pizza box I ripped apart. That was on a cookie sheet too. I had no problems with the oven at all. 300 for 8 or so minutes, and believed me, as soon as the clock ticked over to the eigth minute, they were outta there.
I think the hardest part was the first time you put your light in the oven, wondering if it's gonna melt. Also trying to not get anything on the chrome, and putting it back in without getting caulk on it somewhere. Oh and that damn fourth nut. That's where taking your time comes in. Give yourself a few hours starting with getting the lights out of the truck (stupid fourth nut) to putting them back in. I finished after it was dark because I didn't start until around 7.
It's really no where near as difficult as I thought it was gonna be, especially after doing multiple lights.
If you do mess up a light, you can get some on ebay for really cheap. I bought one with a repaired tab on ebay for $45. It even had the lights with it, so now I have some spares. So all I did was take that one apart, and my messed up one apart, and swapped rear housings. Now I have an extra with a messed up lens due to me, and a broken tab on the back, the light in my truck is good as new, just cleared!
Sorry for the long post, I just know I had alot of questions. Oh, and if you have trouble prying it apart, it's probably because you didn't let it sit long enough, I did that thinking if I left it in more it would melt, it didn't haha.
Good luck.