Honestly, it depends on how you package them. And seriously, 50 in one day is ALOT of work, and sounds like there will be more than that to do if you are co-oping. I know this because we do rabbits (half that in one day is alot, and rabbits are way easier to do), goats, pigs, guineas, and chickens.
If you cut up your chickens, you can fit more in the freezer. I would cut them up and vacuum seal the parts. Soup bones can go in big ziplocs.
One time a university ag dept. had 500 chickens for a project. When the project was over, they offered the chickens to one of the professors. He called my BIL and they butchered them all. Took 6 weekends, dawn til dusk to complete the task. There were only 4 people working, though.
Happy Homesteading Homeschooling Homebirthing Beekeeping Dready (& a bit redneck even) Mama to 4 fab kids : dd (23), dd (13), ds (11), dd (5)