Re: 2 guns 1 scope?
I had a Steyr SSG69, which has its own proprietary dovetail machined into the receiver, and proprietary rings to match. There was a forward "stop" that provided a very consistent and repeatable absolute position for the scope. I could get 10-shot, 1/2 moa groups with that rifle, removing and replacing the scope after each shot.
I tried the same thing two other rifles, one with a Farrell pic rail, the other with a Badger. Not as good. Rifles that are normally 1/2 moa became 1.5 moa.
Try it for yourself, maybe your ring/base combo will be better than mine.
Also, you might could use a pic-rail accessory of some kind, or make one, that provides a deadstop akin to my Steyr, to increase your repeatability.
If I could prove out the repeatability, I'd have no issue swapping scopes routinely. If rezeroing was required each time though...fuck that.