No, you do not have to remove the front bumper, if I recall correctly all the bolts are located on top of the light for removal, maybe one behind the neighboring corner light.
Remove the bulbs and stick an air blow gun or a vacuum inside and im sure it will pull out th moisture evetually.
Also, its condensing on the inside because the headlight is cracked, or there is a leak, most likely from a poorly seated O-Ring from the bulbs themselfs, grease will aid in the seating of the O-rings
Not to be discurraging, but I've already melted two turnsignals and a corner light in my oven!
Stupidly, I put this one in a small toaster oven.
Let me know how well it goes, and how long you bake it! ( I seem to do it too long or too short) The successful turn signal I did, the lens came off with moderate force, but the heat warped it doing so.