Must be claw damage instead of spur then. And they'd still have cockerels if under a year.
Try the double strap design? Better then the single.
I think in your case here, you have to down size the boy group.
I don't have this problem, & I keep lots of roosters.
I'd suggest getting a hen saddle if the boys considered her a favorite.
How many boys do you have? Which one is more behaved?
The damage on her hips look like tears from spurs. Check for extra long spurs, those will need either a trimming, or pulling.