I'd do this as a row quilt, so each row of tractors would be combined with quilting to make a row picture - IE have a road in the front that the tractors are on, and maybe with a few roads going off in the white space, then quilt fields behind the tractors, adding some farm scenes in the white blocks- ie barn, animals, farmhouse. With using perspective, you can give the appears of the buildings being off in the distance so they can be a lot smaller scale than the tractors. I think I'd do most of the quilting in white, or pastel shades so the buildings shows up more, but didn't compete with the tractors.
I've been making a lot of machine embroidery blocks, and this discussing has given me some ideas of how to quilt them.