I'm assuming round bales. If the wagon has a flat bottom it should work fine. I have a SI feed wagon. It has a V bottom and works best with silage or processed hay.
I have one its 20'long with manger sides. We can feed 5-5' bales at a time. We also use it to haul hay during hay baling time can haul 11 bales to the barn. We really like it. I'm sorry we feed 4 bales at a time