With the spinners TKG is talking about, you don't use a spinner nut or safety nut. The bolts or studs with the hole drilled and tapped in the center are for full size spinners. A long thin screw goes through the center of the full size spinner at the point, and into the small tapped hole to hold the spinner on.

As the others have said, you should be able to find a stud, and if it doesn't have threads where the prop rides, that's fine. Don't worry so much about it all coming loose. If you use some red loctite on clean threads, tighten it all down well, and let it sit until the loctite dries you'll never have a problem. It's not really necessary for your stud to tighten up tight against the crank as long as it has plenty of threads into your adapter. This setup will actually be stronger than just using a bolt.

Good luck,
AV8TOR