If you have a look round at chain link fences there's a T junction made that fits into the top of a fence pole and allows a horizontal to be fixed to the top.
ive got a cunning plan (much like bauldric) to utilise one (or perhaps more) on the top of each post, with a small pulley wheel threaded onto the tightening bolt. a rope will co up the centre of the gal post, over the pulley and out one of the open end of the T clamp. the end of the rope will then be tied to the "boom".
the benefit of this will be that i can raise and lower the boom with ease, for harvesting ripe cones as they appear (ive got multiple varieties on the one boom currently) and then raise it back up again.
the rope that will allow me to do this will be isolated from curious bines that would love to climb around and tangle them, as it will be hidden inside the pipe.
I've got a similar system already, without the pulleys. the rope just pops out of the gal pipe at the top. It works, but the rope doesn't like being dragged over a 180° steel corner. The use of the pulleys should reduce the drag but not eliminate it. Another "T clamp" connected after the first may reduce it even further, but u'll see how just the singular one goes first.