Sounds like I have a dent similar to yours. I've avoided getting an estimate because it's probably going to scare me. I just covered the dent and chipped paint with plasti dip. In fact, I just did more paint damage the other day taking 8' railroad ties out of the back of the truck. So I literally just finished plasti dipping top section of the width of the tailgate. Came out pretty good - but you can still see the dent.