well here's a suggestion about the dent above the tail light and i did this with my truck and worked pretty good.
take out the tail light and pull off the bed rail cover thingy's off the top, there should be a hole there, grab a hammer and big ****ing punch then take ur time and pound out as much of the dent as possible. then grab a pair of regular pliers and go in from the tail light hole and squeeze and pull/twist towards you. it should straighten it out fairly decent. at least enough that you can get another tail light in there.i'll see if i can find any pics of what im talking about.
EDIT: this is the best pic i could find, look on the right side above the tail light.