I changed to a 3" sanding disc to do the curved areas. This includes the area above the center line and the very top of the door. Care must be taken not to sand any edges or corners with the DA otherwise you'll likely sand through the primer.
I used a wax and grease remover and a post sanding cleaner before painting. These products are recommended by House of Kolor so I use them. A couple coats of primer sealer was applied to both doors.
I am certain hanging the doors is a two man job but I was able to do it alone using my motorcycle lift. I put a padded Lazy Susan on top of the lift then jacked the door up to height. It worked great. Two would have been better but this worked fine.
Admittedly, there are a couple areas on the doors that require attention. There is one spot on the driver side door that doesn't transition well to the body. It's only about 2 inches long but it will need to be stripped back to bare fiberglass for a proper repair. The other area is just a general clean-up of all the door to body joints. You can see some of it in the photo above. Cleaning up the joints will only require a few swipes of the sandpaper but that act will require us to rethink how the inside lip of the doors will be painted.
Here are pictures of the repaired transition area. This is a blurry photo but it shows how the body line doesn't transition well between the door and the body. The body line on the door became soft from too much sanding. The door is on left side of the picture.
I decided to make the repair using our Icing finishing putty. I protected the body with tape then bridged the gap using a plastic spatula. I cut the putty at the gap with an Exacto knife just as it started to set.
The transition between the body and the door is now very nice and the body line is identical on both sides.