Need some suggestions...

[AndyL]

I'd second the garage door opener (if you don't mind old - I may even be able to chase one down for ya for pretty much free).

Size wise, you're talking the box at the end of the rail - roughly 12x10x8" (that could even be pared down some if you removed the cover and ancillary junk). you'd have limit switches. And Dave would probably have a hoot with the remote

Andy