Bob, I will bet you will find that it takes two layers of brass tubing.

I have done this with zero issues on three jets. My eurofighter was this way, I built a Boomerang XL for a guy and did it on his, and my latest Isobar is temporarily that way till the wheels and brakes I want show up and I don't know when that will be.

You can cut a small circle in the two shimmed brass tubes and run your set screw straight to the axle.

PS, how cool I figured out your delimma