Neat design..... but typing on a keyboard and yanking on a joystick are two different things.
Yeah, very true. I think that would have to be modified regardless; most people's CPs (more than 1P) are wider than a keyboard, right? The extra width on the machine would go a long way, I think.
Anyway, I think the main thing to consider is making sure the cab isn't top heavy. Enough weight in the bottom is the best way to keep it from tipping over; overall stability is a different problem to tackle, really. Of course, I haven't built an upright myself, so that's just my presumption, FWIW.