I'm lookin at mowin approx 20 acres of field grass which is pretty straight forward and easy. Field is to be mowed to a height of 6" and not to exceed 12". Was thinkin about doin it with either a 72" or a 60" bush hog pulled behind a 25-30hp kubota. Never using this set up before I really don't know how long it will take per acre to mow. Any help would be appreciated. This would help me with my bid.