Hmm. I take it you have either a small back yard or the property slopes rather steeply.
The antenna on the roof is not a bad idea. However, most techs will not scale a steep roof like that. Especially if it's a two story house.
Even if one would accomplish this feat, the issue then becomes serviceability. If there is a malfunction or other need to get to a dish, chances are the tech that comes out will not scale your roof.
That leaves you with a pole mount.
Be advised, even a schedule 40 1 5/8' pole greater than ten feet above ground will sway in even moderate( greater than 15 mph) winds. Of course this could become a signal issue.
Since most pipe comes in 10 ft lengths, I suggest going ot an electrical supply house and buy electrical conduit which is schedule 40.. There, you'll find the correct diameter material and it can be found in 12 ft lengths. I have one in my garage right now....I used it to mount a dish at a friends apartment.
The 12 footer should allow enough of the material in the ground to offer a very sturdy mount.
I would drill holes in the part that will be below grade. Buy some short pieces of rebar or use those giant galvanized nails for fastening tie walls together. Slide them though the holes in the conduit and place the post into the hole. Pour your concrete.....I guarantee, if there is a tornado, the only thing left standing will be that pole.
