If you start with the model number and a VIN for a trailer that has the door you want, and you have exact measurements of that door, you can probably order one just like it from Heartland Parts Dep't.
BUT....you'll be completely on your own to ensure that it fits correctly and matches the other woodwork. And no telling if it'll come with the frame or hinges, or knobs, or other hardware that might be needed. Maybe...maybe not.
And I'm sure Heartland would not take it back if there was an error.