Well, as explained in the manual: The flight deck and the PAX cabin models are extremely detailed and consist of hundreds thousands of
polygons each. So due to FSX limitation the PAX cabin is separated from the flight deck as an independent aircraft. To use the PAX cabin select the 777 Passenger cabin from FSX Aircraft menu.

"Sacrificing a little quality" is not an option.
Probably we'll make some cropped version of the cabin (whatever FSX will allow) attached to the flight deck.
So most likely we'll offer the following options in ACE:
- Flight deck only
- Flight deck + cropped cabin
- Complete cabin (no flight deck)