Guys,
A few things to consider. As to the exact site where Rick Wolffe and the rest discovered the remnants of the course, I will email him and see if he remembers exactly which island was involved.
I would suggest that becoming convinced that it is Depew because it is some 400 acres in size matching that aspect of Tilly's description may be incorrect for a number of reasons.
For those that can access the November 1926 issue of Golf Illustrated which contains the article on Poxono (if you can't let me know and I'll email it to you) Tilly used three illustrations. It is the ones of the different par threes that give strong hints that it was on Poxono Island that a portion of the course was built.
In figure 2 (sorry guys, I still can't figure out how to post the images) it shows a par-three that sits at the tip of the island at the intersection of the Delaware River and it's Binniekill. (For those that don't know, a Binniekill is an off-shoot of a river that leaves the main stream and returns to it and thus forming the island. Too small to be considered a river on it's own.)
The key feature of the illustration is that it contains a BRIDGE to be constructed that would take the golfer across the water to the next tee. In other words, the course was designed and built just as Shawnee was; on BOTH side of the river. This means that even though there is only 100+ acres on Poxono Island that it didn't have to contain the entire course.
The illustration also depicts the bridge to be to the right-side of the green as it sits on the tip of land used. This would make sense especially as the clubhouse would have to be reasonably close to the only road nearby and that area of the mainland, as seen in the aerial, is somewhat flat and was being farmed. It is also on the side of the river where the road runs by.
In addition, Tilly describes the tee shot as being from a bluff looking down on "nothing but a green and a causeway leading down to it..."
The Third illustration is of another par-three, this one being the 2nd hole. That too is important as is the description of where it was located. It was built, "on the banks of the DELAWARE..." In other words, with the river flowing along the length of the hole, this would mean that it would have to be on the opposite side of the island from the other illustrated par-three. There is also an inlet of the Delaware that the golfer would have to hit across to reach the green.
If one looks at the aerial of Poxono Island, in the lower left corner is an inlet of the Delaware. Due to rains and flooding that have plagued the area, it would be easy to accept that this was once a small inlet that has become enlarged over the years. It also allows for both a first hole leading to it where the tee may have been a short distance from another bridge leading back to where the clubhouse was at the main road.
Finally, it was named "Poxono" after all. It doesn't seem to be reasonable that it would have been built on Depew and named after another island.
Of course all of this marvelous reasoning may be incorrect! I'll let you know after I speak with Rick!
Ian, you were wondering if maybe the original plans still exist. It doesn't appear that they do. All of Tilly's original personal drawings and copies, along with his papers, notes and correspondences that survived his death were derstroyed in a fire in the 1950's. They had been stored away in a barn on the property where his daughter and son-in-law (the Brown's) lived in Minnesota.
That is another reason why the Tillinghast Association is expanding our website and placing as many copies of writings, documents, and in coming days ahead, blueprints and drawings of his designs. Please visit the site and enjoy what you can learn...
By the way, not a single penny to pay for this work or site has been asked from anyone, especially the membership. The Board of Directors of the Association feels very strongly that it is a privilege to be of whatever aid they can to those who want to learn about Tilly.