I'm assuming that the door assemblies are similar on all models. I installed a screen door on my Falcon shell and it was well worth the price I paid to Ben at ATC. At the same time I changed the "guts" on the fantastic roof vent to make it a fan version. World of difference in ventilation!!!
The screen door is part of a door assembly and. as far as I could tell, can't be added without replacing the whole door frame and entry door.
The new door frame was a bit narrower than the original but, since these are custom made at the factory, the measurement error was mine. I should have pulled off the inside trim and given them the dimensions of the cutout as well as the dimensions of the inside of the door frame. A little extra caulk along the inside edges solved any leak problems. The new door assembly is thicker than the original thus protruding inside but that was no big deal, just got creative when reinstalling the trim.
Removal was simple, I just removed the screws and carefully broke the seal. I injected a bit of silicone caulk into all the old holes "just in case". I used both RV putty tape and some caulk when I reinstalled the new door with new screws.
I wish I had taken pictures of the procedure. It would make a good "tech tip".
Rob