Something else that you might try is a spinner with a thinner back plate.
 Check the Tower Hobbies web site as Great Planes makes one that I use a lot, and this is one of the reasons...

Thanks guys. If Gil's suggestion doesn't work out for me, I'll get a sketch together for you, Dick. I appreciate your generous offer.
Rusty

That's a good spinner, Rusty. A bit of a hassle to get the prop aligned, but not too terrible. A lot of guys throw out the funny metric screws and tap the backplate to 4-40 and use socket head cap screws...a real good idea! To my way of thinking, any spinner with a plastic backplate sux...

I often use this (see link) prop nut/washer from Dave Brown products. The washer is hardened and the nut is stepped, so can screw onto more threads on the crank snout. When I use a Randy Aero spinner, I use a Gr.8 SAE flatwasher and a steel 1/4-28 coupler nut from the hardware store.   Steve

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXB952&P=7