Jubilee was among fiberglass campers produced with a flat entry door. It mounts on a narrow flat recessed flange molded into the shell. See photo
I had to remove the door assembly so a new refrigerator
could through the opening. The old door and frame are salvageable but require significant work to restore. Alternatively a new flat door is available in made-to-order sizes.
Researching replacements, doors are available from Lippert Components and Challenger Door. Interestingly, Lippert "acquired" Challenger in 2020 but so far they are still producing independently.
Challenger Door Series 450 includes a screen door and the entry door can be specified with an internal frame. https://www.challengerdoor.com/entrance-doors/
That sounds good. RV dealers in the area don't stock doors so it isn't possible to see one in person and the website photos aren't rich in detail.
Has anyone had experience with Lippert or Challenger Door? I'd appreciate other suggestions as well.