garytenorsinger - You could consider taking a piece of aluminum plate, cutting it large enough to cover the existing bracket holes plus a little around the edges so you have a firm base to anchor the plate into new holes. Then attach the door cylinder bracket to the aluminum plate. If easier you can do in reverse order, namely attach cylinder bracket to the aluminum plate with small bolts and nuts, then attach the aluminum plate to the door. On my Georgetown XL when the awning is extended, the cylinder keeps the door from slamming into the awning rail. My XL is a 2014 so your setup may be appreciably different negating the usefulness of my suggestion. Good luck!
John & Gloria Hunsaker FROG Member CA-0030-988
2014 Georgetown XL 334QS (class A with 4 slides)
2013 Smart Car TOAD
Blue Ox Aventa LX tow bar, base plates, diode kit
SMI Stay-IN-Play Duo auxiliary braking system
25' Off shore blue water fishing boat