Owned a boat yard in Fl for twenty years. The "ding" appears to be cosmetic. If there is plywood under the damaged area as suggested it should be laminated to the back of the damaged area. This could be the PO problem with coach handling thus second time around. Yes, most marina/boat yards can effectively repair the area to new like status. Since the area is a curved, bumper I would reccomend the use of West Epoxy. This product in itself has mechanical strength far superior to any polyester resin. Estimate for average repair with poly, 400.00 to 500.00, using West System add 200. To 300. Personally I would use it as a bargaining tool. Have the seller knock 5 two 8 hundred off, find a small shop tell them you want to use West epoxy this will save you money especially this time of the year. Word of caution if in northern climate this time of the year the work needs to be inside heated environment to cure correctly. Good luck!
Clay & Pebble
2012 Providence 42 M. Spartan Chassis, 450 ISL
Ford Edge toad, RM All Terrane, TST TPMS, SMI Air Force One, RVM95....