Gear? Robart won't even talk to you for a model that size. The gear they have now, that retract similar to the Goose, is the F4F. Very different, not even close. My guess is there's none available anyway.
Robart used to make 1/4 scale Widgeon gear...pretty close to the Goose. There was a 1/4 scale G&P widgeon kit that Robart had gear for, plus another giant scale Wideon that was kitted here in North Texas.
I am certain that Century Jet or Sierra Precision could custom make gear for any size Goose, for a price.
Nothing wrong with offering the plans at any size he desires. Remember, for every model built from a set of plans, at least 10-100 sets of plans gets sold to those who dream about building it. I have about 100 plans myself that I might never get around to building....
I agree that he should offer it in a more rational size, as well...but the nice thing about CAD is that doing so becomes a pretty simple scaling exercise, plus some new considerations for sizes of structural materials.