I would recommend Norwegian Jaerhons for baloneys. They are small but lay lots of medium to large eggs. They can be very tame and they are auto-sexing so you will not accidently get a rooster. Three hens would do fine in a small tractor.
You would also have to eliminate the blue egg gene. Just a thought: Greenfire may have already tried this thus the green eggs showing up in some Rhodebars. Niclandia would you come over to the Norwegian Jaerhons to answer some questions...