Nice job, @papa-pepper. Three jobs are done at once. I do the same around here. Don't waste anything and if you can do one job and be able to start a second or third at the same time, so much the better.
I have been studying your pillars. I really like the idea of using up the stones on the property to make the posts perhaps stronger, but also look quite attractive. But I have a question. The wire you are using to form the cage to fill with the rocks, is it galvanised or does it have some form of rust proofing? Here, that is something we need to think about because of the salt in the air. In Canada, we had to be aware of salt from the roads. Roads are generally heavily salted and then the snow/salt mixture is plowed back to the fence-lines.
I would hate to think you do allthat work to have to redo it because of rust. I have seen one other place in my travels that used a similar method, but they used a cement slurry poured down the center to help hold the rocks in place. Just some thoughts...
I have seen this type of wire rust eventually. I figured that eventually I may have to rewrap them, but I'm thinking I've got a lot of years before I need to worry about that.