I suspect the door is a laminated door, so you probably can't do a whole lot to rebuild it without having materials to redo the whole thing. At that point, I think you're better off just having a new one made.
I did some very special research for you and found out the manufacturer of the door was Nappanee Door. Nappanee door is now out of business, but they were bought out by Lippert Components (LCI), which is a big supplier to the RV industry:
The hinge system looks like the same or similar to what was used, so I'm thinking it's the same style.
The bad part is it would probably be in your best interest to go to Goshen to pick up the door because the cost of shipping it somewhere would be high. I suspect it would have to be crated and go truck freight, which it risks getting damaged. Plus not many truck freight companies will deliver to a private residence. I'm not sure where you are located, hopefully it won't be too far away.
Before you take the trailer to get the new door put on, search out a sign/graphics shop and ideally take it to them to see if they can match the color of the swoops on the door. I know they would love to template the pieces on the door there so they could make you some new ones, then all you'd have to do is stick them on when you get the door. Fortunately you don't need to worry about it having to cover a shadow from the old one or something. Take lots of pictures and a few measurements and this should go pretty easy.
I did find out the opening frame for the door was made locally to Sunline though. So be careful with that when you remove/install the doors.
2007 T-286SR Cherry/Granola, #6236, original owner, current mileage: 9467.8 (as of 5/26/19)
1997 T-2653 Blue Denim, #5471
1979 12 1/2' MC, Beige & Avocado, #4639
Past Sunlines: '97 T-2653 #5089, '94 T-2251, '86 T-1550, '94 T-2363, '98 T-270SR