Absolutely, reasonable space indeed... I have done closeup inspections of AM broadcast towers as well as medium power FM stations, but not approached any closer than about 20 feet from the FM antenna and stayed out of it's main pattern (AM stations are no threat). By "main pattern" I mean above or below it, not directly horizontally in front of it. If it's a directional radiator you could feel safe approaching closer from behind. I would not worry about the 330kv transmission line, but I would be VERY APPREHENSIVE about approaching a TV transmitting antenna. They run very high peak ERP (megawatts) with a digital signal that could very easily scramble electronics. Your drone could to anything from completely shutting down to gyrating wildly out of control to the ground. If you're doing this inspection of a TV transmitting antenna at the request of the station owner coordinate a shutdown of the transmitter during the inspection. If they won't do it, sign an agreement with them to replace the drone in case of failure. Make good use of zoom.