Your no power situation is your biggest issue. There are ways of getting your signal to a remote building on your property, but they all require power at the remote building for the network components and the camera. With some expense ($250?), you could go solar, but that may also attract any unwelcome visitors you want to watch out for. If you go solar, you will need 5 V for the camera, and possibly 12 V for any networking equipment. Something like this will require end-to-end planning before you buy anything.
All that said, here are some threads that may be of interest:
Adding solar power:
Ubiquiti NanoStation Loco M2 network transmitter:
Powerline Adapter for buildings with power that are also on your meter: