I've actually had this idea for a while though I don't think I (or anyone else) have ever posted it. If you have sorry, if not and you thought of it already please don't post "dude that's old news, I already thought of that" because that just gets under my skin.

Part of the problem with removable panels is it is just a pain in the butt to plug/unplug control panels. Well, here is the solution.
Cordless Panels.
The best way to have cordless panels is if an encoder maker (Andy Warne?) would make a cordless encoder like the IPAC. Problem with this is it would be expensive providing you need an encoder for every panel. I don't know of any right now so my next idea is to use cordless gamepads. I haven't looked at too many but I know they do exist. Some are usb and you can use multiple ones so you could have enough controls. For spinners and trackballs you can use cordless mice.
What you do is actually mount the gamepads/mice on the underside of the panel and have the actual receiver on the inside of the cab. You can actually use the same receivers for the panels if you can configure the frequency they use.
Offer suggestions here for gamepads to use or other ideas.