I don't disassemble mine. I just fold it flat and put it on top of the other gear. I also have a small one I built myself out of old parts that folds flat and takes very little room. Sets up in seconds.
Drive over and check 'em out!
DonM

If you really need to immobilize your head THAT much and can't sit down and play, surely even driving to the gig is going to be more of a problem than the gig itself?

The one thing I might suggest is a visit to a GOOD piano teacher, and perhaps talk about your sitting posture. So many of us develop bad habits over the years, and slump over the keyboard, hang our heads down, etc., and having a professional take a look at it and maybe work on it with you would allow you to still remain seated.

I stood and played for most of my career, and I don't think it ever helped me stay stiller!

I echo Tony Mads' sentiments, and add that you could probably just add an adjustable second tier to your current stand. They are available for most stands 'Z', 'X' etc. and it would seem to be the most economical way to go.
Ciao,
Jerry