I allowed just two chickens at a time to roam my vegetable garden some last summer after it was in full bloom and they could no longer eat a new plant down to the ground.
My garden is huge, and just two chickens at a time didn't do too much damage -- especially since I was feeding everybody an afternoon snack of diced, less than perfect garden tomatoes and watermelon (I'd cut off the bad parts, and feed them the rest).
That helped to curb their appetite for the fruits still on the plants. And the fact that only two were allowed out at one time meant that the garden wasn't run over by a feathered wrecking crew.
In this month's Backyard Poultry magazine, they had a picture of little mobile chicken tractors that looked very easy to build. The ones they showed were only size enough for one rooster, and using these little mobile coops, they were able to house their otherwise unwanted roosters -- and get the roosters to work only the parts of their garden/lawn that they wanted the birds to work.
The only other option I can see for you is to confine them 23 hours a day, but let some or all of them out for an hour of SUPERVISED free range time right before dark.
I've done that one too, with moderate success.