Looks like your lowest elevation would be in the area of 30 degrees. So simple said.....60 feet away from your dish los you could not have objects higher than 30 feet in height. Now i would guess you would have to apply the los in a 20 degree fan. But I'm not sure about the degree spread that the dish views. I come to that conclusion by satellite degrees 99 - 119. Like i said though, i'm not sure of the view spread, but 30 dgrees in 60 feet will offset the original point by 30 feet.
