I don't know if it will work, but I entered a positive "pension" (ie, rental income) starting in 2015 and a second equivalent negative pension "starting" in 2017 and FIRECALC seems to have accepted the entry. Don't know if that will handle your interim rental income or not, but something to try. You can also enter a lump sum to sell your rental income property and what year in Portfolio Changes - as you probably already know. Good luck...
No one agrees with other people's opinions; they merely agree with their own opinions -- expressed by somebody else. Sydney Tremayne
Retired Jun 2011 at age 57
Target AA: 60% equity funds / 35% bond funds / 5% cash
Target WR: Approx 2.5% Approx 20% SI (secure income, SS only)