I’m not entirely sure if using variations would be so very helpful for this purpose…
in my opinion, what he asks for is “radio buttons” - sounds like the typical use case.
@Craiger: Unfortunately, this button-behaviour can actually only be achieved by using GP-Script.
I once wrote an example script which also contains some remarks in the code… maybe this might help you with your rackspace?! (which looks quite nice! 
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How to realize “radio buttons” with scripting - User scripts - Gig Performer Community
If you have questions, feel free to ask!
Oh, and welcome to the GP-Family! 