When we picked this unit up it had a number of Good Sam stickers at strange places to cover up dings. It also was missing about 8 inches of the lower front body panel just in back of the right front wheel and the body panel under the door was badly damaged as was the aluminum frame under the door.
While sitting out on the desert I started doing some of these repairs, Work was somewhat slowed by a sore knee that limited my movement and at one point had me flat on my back for 2 days after stepping out of the Yellow Submarine and twisting the knee.
The first project was to repair the small body panel in back of the front tire. I did this by first removing the panel under the door and using a large crescent wrench and a hammer straitened the aluminum frame. Then I ground out the cracks in this small panel from the back and lay in multiple layers of glass cloth to repair the damage. After the back was repaired a little sanding on the front and some body filler completed the panel and it was glued and riveted back in place.
The real challenge was replacing the missing portions of the front body panel. This was done by first feathering the edges around the missing glass from the front using a small disk sander on a battery drill, then building up a block of urethane insulating foam and gluing it in position from behind so that it stuck out past the original surface. It was then sawed and sanded into a rough shape and then using some cardboard templates cut to match the other side the foam was sanded to a final shape that matched reasonable closely.
When the foam was properly shaped a couple layers of glass were added from the front. After the first layers of glass had set up the foam was broken and sanded out from behind and more layers of glass were added from the back to give it lots of strength. the job was completed by using some fine auto body putty called glazing compound and then sanded smooth
The same technique was used for smaller repairs where glass was missing.
Note that you must use urethane foam for this type of repair as other foams will tend to melt when resin comes in contact with it. Also urethane foam is very soft and easy to shape with sand paper, file or saw.