I always thought they were crouching under the floor with maybe 4 feet of room, I've seen some diagrams that make it seem not so outragous, I don't think the cockpit was that much bigger than the exterior set, maybe 25 percent bigger. But also from the page above is how things can fit.
http://web.archive.org/web/20010426005359/www.synicon.com.au/sw/mf/mfplan.htm
Scroll halfway down to see how people could fit in the falcon.
Sorry off topic!