Why would the AF limit size and make these sims on rail cars ? Just build all the sims and schools at one or two bases , and ship the pilots in . Edwards comes to mind as it's big enough to do everything with anything .
These were SAC units, and Edwards wasn't a SAC base.
As for the size, cockpits aren't that big. These weren't full motion sims, but crew station simulators. And the cost of the simulators was expensive, guessing they still are, but it was easier to ship these to various SAC bases around the country and have the crews cycle through. As for sending the crews, the issues was at the time these were in place, SAC crews were sitting on 24 hour alert duty, which FYI sucks...its boring days of doing nothing. You are limited to where and when you can go places as if the Klaxon sounds, you have a limited amount of time to get the jet airborne.
As for these cars, I got a bunch of photos of the cars on display at Fairchild while I was stationed there a few years back. Been looking at doing a 2 car set. Thinking a Troop Kitchen car and an MTL heavy weight for the two.