Any question answered...

I'd rather have lock nuts that grip the track ends

I know, but you're wrong to want that :)

asking if anyone knew where to get some that will fit my hubs

Make a mandrel to hold the stock parts, chuck them up in your lathe, face off 4mm, chuck them in your dividing head on the mill and re-cut the wrench flats, reassemble and fill up the space with Shimano lock nuts.

I think the actual problem isn't the smooth lock nuts, even if you refuse to see sense on the chain tug issue, it's your track ends. If they are not flat, smooth and parallel, you're constantly fighting the desire of the lock nut to skate across the high points and drop into the low points.