nolimit
I don't know how many times you operated such flights. Certainly, EK tried 3 man ops on JFK and BOS, but was confronted with too many fatigue reports. (YYZ is 48h i guess?).
ORD is different because you have an additional time zone and still only some 24h rest. Those who have done it know that it makes a difference.....
We are struggling with fatiguing rosters. Stunts with 3 men had to be abandoned due to fatigue. People fly 90h+, not the case when above stunts were tried. ORD has the most fatigue reports, closely followed by JFK due to the bunk position (gets slowly solved, thks).
Looking at the whole situation it is not very wise, politely put, to agree to go on 3 men. The slightest mistake gives any authority a blank check to blame the skipper having gone over the limits and pretending he shouldn't have, pointing to all the points i have listed.
Just think about it! No one, especially nobody from the company will come to your rescue.