Indeed. I happen to be a craft beer enthusiast and a music enthusiast. So, combining those things during a show brings me a lot of joy. I'm curious how much of the "no drinking onstage" is puritanical opinions versus an overabundance of caution or perceived 'professionalism'. In any case, I don't know many people that go on stage without a beverage - beer, water, coffee, whatever. Not seeing a player with something to sip on is the exception (not the rule) in my experience.
Keep us posted! The vibration issue is why I am primarily focused on cup-holder-like devices. (I'm not just looking for a flat surface to set a beer on - I can do that on the floor, albeit at risk of kicking it over or knocking it down with a cable.)
So far, the fold down plastic one from the first page is top of my list, since it could be secured to the side of my cab with multiple 3M command strips. Those hold 12-16 lbs, and a pint of beer in a glass is ~1 lb. Plus, those holders can fold up and my cab cover should still fit without an issue. I like the screwed in one pictured with two drink holders for water and beer, but I don't really want to permanently alter my cab. The other idea is buying one of the guitar hangers that mounts onto a cab handle, and then modifying that with a cup-holder instead.