cutting out filler plates

Ahoy, I sanded down my tail light area only to find and ass load of bondo in both corners. The bed around this area is pretty messed up and the filler plates need to be replaced or repaired. I was thinking I might as well just cut the fillers out and put in some stock tails. Would I be able to do this easily? How do stock lights attach to the bed?

Josh

depends how bad they messed it up, might just be easier and cheaper time wise to get a ne bed.