Some here have undoubtedly grasped the idea, just dawned on me.
Yes I know we are very fortunate.
Fortunately it appears we've won the game, so most of our nest egg will go to our heirs and charity. My target AA was 50:50, but our taxable account is well over half our total.
It has really bothered me 5+ years that our stock allocation just keeps growing with no good way to stop it - for the first 60+ years of my life I considered that a good thing of course. It doesn't make sense for me to continue rebalancing, it just generates more taxes while I am already struggling to avoid higher brackets/IRMAA. All our equity funds have huge embedded capital gains, there's almost no chance I'd ever have a loss to use for tax purposes. I stopped reinvesting dividends years ago, all my charitable contributions are QCDs now, too old for DAFs, and our IRAs are already all fixed income. My stock allocation is now 63%...
Of course it will fluctuate, but I'm coming around to the realization that it may be OK to let our stock AA drift up for the rest of our lives. Our AA is no longer what we need, it's become what benefits our heirs and charities. Given they are younger, a higher stock exposure for the next 10-20 years is probably a good idea. They'll probably inherit more, and if things go seriously south, it won't hurt us - and while the heirs will get less, they have no idea what they're probably going to inherit anyway (they'll never realize it could have been more or less). And they'll have benefit of stepped up basis on all our holdings, something we'll never see again.
I may finally stop letting "equity creep" bother me. Too soon old, too late smart...