I have more than one elaborate Excel sheet ;)
I plan to rely on two PT jobs I already have, two rentals, and my 1/3 share in an LLC that is currently buying rentals and will pay out all profits starting ~4 years from now, leaving TSP/IRA for the safety margin. To model this phased approach, I've tried several different structures. I'm not sure I've settled on one yet, but I enjoy the experimentation.
My latest sheet shows revenue streams (jobs, rentals, pensions, etc) and major costs for each year, given as monthly averages, and sums up to show take-home pay after health care and debt payoffs. It also projects retirement account balances. This allows me to identify key junctures, especially low points, and analyze the effects of any changes. For example, if the low point looks too low, I can delay my ANG retirement, or stay in real estate past 2019 when my rental LLC stops buying properties (I'm our agent so it's basically free money up to that point; afterward it's more like work).
I will probably add a column for spending and use that to sum up surplus income into a taxable account balance. I may also add in SWR-based logic to show "backup" income for each year, giving me a better grasp of the safety margin.
I use present-day dollars and 4% post-inflation returns to keep things simple and conservative.