Yeah, I cannot emphasize enough what moof said. Make sure that under no circumstances does your antenna get anywhere near the power line.
As I am a huge fan of loop antennas, I would see what you can do in that department. This might be a good application for a resonant loop. I'd consider running a loop around the fence (and I guess along the house for the southern side), but then you'd have the power line right over it. Also: Bad for possible noise pickup, and extra bad if the power line falls on the loop.
If you are allowed to use that pine tree in the front, i wonder about putting a dipole from it, to the top of the chimney, then down to the shed. Looks like there's enough room for a 43 mb dipole that way - maybe? Otherwise, same dipole idea but going down to the ground near the tree, maybe in front of it of needed. Not ideal, but at least you have an outside antenna, and could run coax to it.
I feel for you guys with overhead power lines.