I agree, you don't want that many boys, and the pullets definitely don't. Until they're laying they're not ready for mating, so it's stressful for them with just one amorous cockerel, let alone several.
As you remove cockerels, formerly timid boys will get more confident to go after the girls too (testes size is suppressed by the presence of dominant males, so they have less testosterone now than they will have).
If you can't separate the cockerels, I would make your choice of roo as quickly as you possibly can to spare the girls, and just pick one.