Power lines prob won't affect it, unless one of your sats happens to line up exactly behind a power pole, lol. I would be more concerned about how close it is to the roadway/right of way.
Its hard to tell there. To be sure, I would determine if it's a city, county or state roadway, and call the appropriate highway dept, ask how much ROW that particular road has. If it's 40', then you have 20'from center line in either direction. If you're sure it's your land already and not in the right of way, go for it. (or get a good chain saw!)