thx for the details, we are on the same page.

Actually became motivated when i noticed how IRMAA was hitting relatives on their 2020 taxes and morningstar hosted an excellent podcast in ~2022. (noting these stealth taxes are ones all political parties increase at the highest nonlinear rates since voters dont know\understand them)

Had no plans to ever hit RMD events, but wanted to find an 'optimal' rate where i could fund the Roth (conversion) taxes with already sufficient non-retirement liquidity.
due to some quirks, i have a few years prior to medicare where my earned income will dip in a very predictable manner, while my taxable investment income may change by an estimated +/- 30% annually.
issue is whether this gap will be enough years to split up the tIRA (now also holds converted 401k). want to avoid my Roth conversion years annoyingly becoming my highest tax years, and so am thinking i need to quantitatively schedule smaller amounts even a few years before the upcoming earned income dip.

Given the uncertainties and complexities at play, i was looking for a probability weighted models considering current\future interest and marginal tax rate patterns. monte carlo models for retirement planning was a major breakthrough* 20+ years ago, but that technology should be (hopefully) surpassed by now with a tool for this specific issue of Roth conversion.

All of this could be stymied by more retrospective congressional changes to Roth, which we have seen start with the 10yr inherited limit.

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*en.wikipedia.org - Edelman Financial Engines