[Don Plumley]

That will be nice. Two post structures are tough - the load gets distributed unequally very easily. Take a straw and bend it into a U shape - see how easily forces at any angle causes the structure to collapse.

You might consider 8" round posts. If you bury the treated posts, make sure the concrete at the top slightly slopes away to help keep water out. I prefer deep concrete footings and strap anchors that are bolted to the posts - that way if/when someone or something knocks it over, you don't have to pour new footings or bury new posts that are part of the structure.

A big part of the project is how he organizes and coordinates others to help (I'm an Eagle Scout). That always seemed the hardest part of other projects I've seen.

Good luck, and Congrats Sherwood