Do you find a stand decouples enough or do you find problems with the typical hollow stage? One problem with the AKG P2 is that it can't mount in a "rubber band" type decoupler

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Ooo, I stay well away from the rubber band decouplers unless I'm recording at home or in our rehearsal / recording space. I had one fail and nothing says I hate you quite like a nice live condenser mic falling onto a drum set ... The 421 which is my choice for bass guitar uses a hard connection point anyway. Probably somewhat like the P2 in that regard.
I carry some extra carpet fragments with me for the kick and bass mic's - if I'm using the mic which is not all the time. In my FOH, I am setup for aux fed subs which in and of itself helps with mic stand rumble. Yes, the kick and bass guitar are still stage coupled but getting rid of all the other sources seems to be a step in the right direction.
I also DI the bass. Any sound guy that can reliably fog the mirror will. If, just if the kick, the bass and the stage just can't get along, the DI while not a perfect solution may save the day. It isn't like I get to mix Paul Simon (all hail JJ) or Jimmy M for that matter. There are often time constraints to be lived within. The economics reality of the gig's I do means 2 hour setups are a luxury... If I didn't think it would create as many problems as it solved, I might back line a bass rig.
Note that I am not flying a major line array setup. The big boys hate aux fed subs for some pretty good reasons. For the local / regional small sound company stuff, it is a viable tool in the arsenal.
I personally don't get the love for an sm-57 on a bass cab but that must be a manifestation of my alleged Shure-hate

i consider it kinda like strings. I could play old D'Addario XL's but I prefer fresh TI's. Or pickups, a MiM J or one with Lollars or Fralins... Yeah, you gotta spend but there simply is no substitute for a great sounding audio source...