I have some experience in this. Only a 4ft one? You want a Bushhog wider than the tractors rear tires. What HP tractor do you have?
In typical fashion.....The only time you use the full width of the cut is on the 1st lap around. Then you overlap....Thats just the way it is. You don't want to have to rub the tires or fenders on things and you will if the Bushhog is only as wide as the rear tires. Used Bushhogs.......Bushhogs are some of the most abused pieces of equipment out there. I'd highly suggest New. Yes your tractor may say, designed for 4ft Bushhog? You just use common sense. If its Super thick, You may have to make a high cut and low cut in some spots.... But believe me.....You want the Bushhog deck wider than the tractor. I use to pull a 5ft with a 16HP Kubota.