One of these days some enterprising keyboard manufacturer is going to design a remote keyboard with all the controls to the left and right of the keyboard. Sure, it would make for a long keyboard, but it would allow you to stack it underneath the main keyboard at close to organ spacing...

I'm fed up of having to have the keyboards separated by a foot or more, just so you can see the display and controls. Anyone who has played a B3 or home organ (or both at the same time if you are Russ ) knows how easy it is to switch manuals when they are THAT close together