There's no way any of the current DCS stuff would have a chance of fitting into the Plymouth! You could tow it around in a car behind it and probably do OK.
I have one that I'm also going to upgrade, I'll be using the ERR MiniCommander 2 with smoke control.
I'm guessing I may have to do some "creative" alterations to the cab configuration to fit the board in. I'd like to have sound, but I think that's a total pipe dream from looking at it.