We had a job a few years ago with somewhat the same conditions. I don't know what you consider a good distance, but we were about 3,400 ft from the nearest electric source for a dedicated line. So, we collectively contacted the electric company who dropped a line down almost at the
sign itself and was far cheaper for them to do that, then run a 1/2 mile under ground for a connection. I don't know the ins & outs of it, but check with your local electric supplier for options.