Welcome! Sounds like you have a path forard! Hopefully, the next 6 years will be kind to you, both in the real estate, and equities markets! With $2.5M in retirement accounts, and a $4.6K pension, you should be able to have an income of around $155K, less taxes.
Good plan on working on taxable accounts/access to previously taxed $. If I were you, I'd first max out your and your wife's ROTH IRA or ROTH 401(k) as you can withdraw the contributions tax and penalty-free at any time (so be sure to track the basis). Then focus on taxable investments.
If you anticipate selling two rentals before you FIRE, and anticpate having significant taxable gains, then I'd consider converting each rental property into a primary residence to meet the two-year residency requirement and be able to exclude up to $500K per house in captical gains from taxes (MFJ). More details here:
https://www.investopedia.com/ask/ans...inhomesale.asp