This is super exciting, great pictures! I'm looking forward to coming and helping out once I get my projects caught up
enough!
This might be a dumb question but why are you using post hole diggers when you have an excavator? You can compact the soil really well by pushing the
bucket down like knuckles. Then you could place the poles as deep as you like with little effort. If you back-fill and compact 6"-12" at a time I think this would be just as stable (if not more) as undisturbed grade.