My first hole was right at 3 feet minus. I could not dig any further down, so I thought, with a post hole digger. The wind, snow and frost heave pulled the post and 150 # of concrete right out of the ground then broke the dish of the brackets. The second hole went down another two days of digging by post hole digger another foot. The snow, ice (8 to 11 inches) and 90 MPH straight winds bent the dish, then moved the pole, and finally broke the brackets off or loose again. (added another sack of concrete). This time I have gone down to ROCK with a backhoe. Going to add up to 12 - 80# bags of concrete and building a wind break berm and pumphouse to keep as much of the wind as possible off the dish. If this does not work, the next time I will use fixed C-band dishes in concrete walls and hope I get the aim right the first time. Either that or a three point mount could be built for a movable dish, but probably not a "Polar" mount. I really would like to try a radome....
All that to say, it depends on your location. A horizon to horizon line of sight on a mountain (OK, hill) top looked GOOD, but there was a reason there are no trees!