Hi @MultiMartinMusic, I made a monster all purpose rackspace which mixes 8 switchable instruments plugins and a set of reassignable MIDI controllers switches and pedals. You can assign any MIDI keyboard controller to any instrument from the main panel. You can also have different combination/settings stored on a per variation basis. It was thought to explore a bit a different way of using GP which is very close from what you describe. So, take the time to have a look at it (a lot of Scriptlets inside) and check if you can reuse some concepts for your own use case.
e.g.
