Walt, don’t go… we appreciate your advice, but I agree 100% with Gary and the others.
I too can remember back to the days when we had to have something (a circlip, etc) at the end of the axle, outside of the rear hubs.
Was that safe? Absolutely.
Was it overkill? Absolutely.
The fact is that in all those years, I never saw a tightened hub slide out and off the end of the axle… I only ever witnessed them slide inwards… and when you think about the forces acting on the axle and the hubs when a kart corners, it only makes sense. We 3-wheel these things on the outside rear, which is “pushing” the axle further “into” the hub.
Now, if you don’t tighten the hub down, anything can happen, but that would be the case no matter where on the axle the hub was located.