Hey, I am debating on what to do around the back window of my 69the rust has not gone all the way through but I don't want it to come back. can I just grind it down and skim bondo over it or maybe fiberglass. I am new to bodywork so excuse the lack of knowledge. I know I need to replace the door skins because the rust is all the way through on the one and the other has a hole in it where someone dropped something against it. thanks in advance. I have pictures I can post if it would help.