Re: Is this a variable WR option?
I think it would be OK to take an average - I assume you mean to plug the numbers into Firecalc, right? Especially if the first bunch of years would actually have lower withdrawals - to me that would make it conservative, and I like that for projections.
My spreadsheet has all sorts of differing withdrawal amounts - higher travel budget in the first 15 years, lower withdrawals once my pension kicks in, etc. According to it (using conservative rates of return and high health care costs), I'll run out of money around 103. I'm OK with that.
In Firecalc I just plug in my starting expenses and adjust it up for inflation, whereas in reality, costs may go down when you slow down in old age (especially for me when I don't travel as much, because I basically plan to see the world in those early years).
Two roads diverged in a wood, and I - I took the one less travelled by...