Doc, these tortional locknuts may hold tight, but many times hold less securely on each successive use. Using one with inadequate locking force is not good either.
On the flip side, tortional locknuts are also prone to wearing the fastener. hat bolt is not an inexpensive easy to find item.
As for Loctite on axles. I very seldom use it. Two reason, first is contamination. With Loctite, there are many grades, for the most part, all require clean threadeds. If you install an axle through the spacers and bearings dry and clean, you will pick up some residual grease going through. This can render the Loctite ineffective. Second, I always grease the axles to prevent corrosion. So for me, there is no practical way to prevent contamination.
Fiber locknuts could work, but again they wear out. They also suffer loss of locking strength from grease.
The easiest and most secure method is a mechanical key. Either a cotter key, loc wire, or safety pin.