I've got about the same distance to go want to do the same things with cameras and want internet access there also. 

I'd like to mount one on end of building here and point in that direction. No trees to interfere and was thinking about a telescoping flag pole for the other end to match height and get above growing crops. No climbing just lower pole down if anything needs serviced.

Thought about mounting the one here on the peak of the building inside behind ventilation louver made from vinyl siding material but don't know if that decreases power or signal but it keeps it out of the weather also. Already have continuous conduit from that location back to router so it would be best point to send signal from.

Also would like to expand wireless coverage outside to other areas at both locations but think that requires another device.