All recipe calculators provide 0 bitterness from flameout (no hopstand) additions.
If I make my flameout addition, carry my kettle into the house, put the chiller in the kettle, and begin cooling within probably 2-3 minutes is any extracted bitterness pretty much negligible? For some reason, I got in the habit of doing 5 min hop additions because I didn't trust a flameout addition as contributing 0 IBUs.