Shortly, we discovered that we needed a jib on the end of the forks in order to reach out far enough to bring the post into position.
A twelve foot oak which was 10 inches in diameter was chained to the forks.
The posts were now attached to the end of that (jib-log) with a chain that held the post upright.
The bottom of the posts were cut flat with a chain saw. A 1 inch hole was drilled into the center of the log. A 1 inch piece of
rebar was sledge hammered a foot into the log
Soft dirt was removed in the work site to expose the rock surface just below it by six inches.
A 1 inch hole was dug into the rock with a gas powered drill to a depth of one foot. The poles were stood. The pins (rebar) went in to the holes. The poles were leveled and braced.
The first attempt of setting one upward (before we put the jib on the forks).
The fork boom did not reach out far enough. It was then that someone came up with the wooden jib idea, which extended the reach to be able to set the three rear poles.