wow, you are of a like mind to me! I like to plan out my finances the way you have described. I do not want any surprises (never did). So I totally and completely understand what you want. I also think that it is entirely a reasonable and realistic desire to do what you described, and is certainly possible. It just takes some work for research and understanding, and then crunching some numbers.
I learned over my long working career to do things for myself, and for learning purposes, such as deciphering things like the tax withholding on my payroll checks, doing my own income tax returns (until about 15 years ago), and other basic personal finance tasks, and then got into more complex issues. Are you familiar with spreadsheets? (such as Microsoft Excel, QuattroPro, etc, or the free options, like Open Office, Google Sheets, etc) If so, you will find these make your work so much easier.
Are you going to be covered under Medicare? If so, are you younger than 65? The answers to these are big ones and may affect your considerations. If you won't be, or are too young, you may want to review the rules for the ACA refundable tax credit for your health insurance.
As mentioned, I have spreadsheets covering all my personal financial planning and I use them to project my future income considering my pension, Social Security retirement benefits (for me, and my wife's spousal), RMDs on IRA's, expected returns on other investments, etc. The counterpoint to this is I also have spreadsheets to determine my expected future income tax, considering how much of the Social Security benefit may be (will be) taxed. And these are combined in my mega-budget spreadsheet that extends out for our projected lifetimes. We use this to determine what we can afford each year now that we are in "spend down" mode. (What can I say? I have an engineer's mind for 'ciphering' and this is my hobby. haha) I know others who do this same sort of thing. So it it possible and practical and certainly you can do this.
Fortunately, you know what your pension and Social Security (will you get SS?) will be. You mentioned the SS offset, is this the WEP and/or the GPO? I'm sure you should be able to get a clear answer on your state/local pension on the benefit amount. You can review the WEP and GOP, if applicable, starting with these SS documents:
Once you know your income you can work on your income tax liability. One guide for you are your previous income tax returns. Of course, these are based on your working income so that is a difference. But I would review them and see how the instructions cover your income in your newly retired situation: Social Security, pensions, etc. You may have to search through the IRS website (which is really quite helpful) and the North Carolina state site for information on rules and for tax forms. I would fill out some "trial" returns, even if they're for 2020 rather than later years, and see what rules apply to your income and what the taxes should be.
If you have questions on that process I'm sure you can come back here and ask for further help on this project.
I wonder if you can contact any of your working colleagues who are now retired and ask for their input on how to work through the rules of all these bureaucracies?