I made some decent progress on the secondary hull in the last couple of days. I'm building most of it as a single Sub-D object, as you can see from the following sequence of images:
I stuck a 6' human figure on the fantail as a scale reference. Originally, I thought the hangar deck opening looked like it wasn't tall enough but it's actually more than 26' high. Also, I think the fantail is jutting out there a bit too far so I'm probably going to shorten it by about half.
In case you're wondering, the hangar deck control booth is going to go in the box directly above the hangar doors. Neither the doors nor the details on the fantail are final.