Opportunity cost of RMD tax reduction strategy

Appreciate the board’s thoughts on the following

Context:
Will retire at 55.
Pension at 65.
SS at 70.
RMD at 75.

Plan is to put cash from Severance, et al. into tax free (Muni’s) acct and draw from it for 1st 4-6 years of retirement. In parallel, will convert tax-deferred accts to Roth at lower tax rates (will do this for 1st 10 yrs) to reduce tax deferred balance significantly by the time of RMD, thus reducing tax at 75.

This makes sense to me to reduce ticking tax bomb when turn 75. About 60% of retirement portfolio is tax deferred.

Pension and SS will cover 100% of expenses at that point so RMD is not needed and it will be taxed at higher bracket rate in those years.

Multiple CFPs have validated. I get it. However, not one has mentioned or calculated the opportunity cost of paying taxes years 1-10, that otherwise would grow over the 20yrs leading up to RMD years.

Challenge my thinking / blind spots, please.
Framing the decision as follows:

PV of opportunity cost - what would those taxes paid in yrs 1-10 have grown to as tax deferred dollars across 20 yrs to RMD?

Vs

The difference in:

PV of taxes applying the tax reduction strategy across RMD years

Vs

PV of taxes without applying the tax reduction strategy across RMD years

Are there any guidelines for what would have to be true for…PV of the opportunity cost > PV of the value created from the tax reduction strategy?

Market returns of X %?
Effective tax rates of Y %?