Why don't you just let your OT go to nest two and you go to nest 4, you already mentioned that he starts tanking so if you just start the fight down at nest 1 while your co tank is tanking you can fly up and take boss and he can still easily get to his nest in time, leaving you with a feather to fly up to nest 4 while your OT takes boss during that time...
that's how we do it
we only have to go to three nests total as tanks in our guild before we start nuking btw, round same ilvl