Ok for a female youth Hunter you said? With a slug? First it depends on how big n strong she is. I have 2 daughters. One is bigger/stronger n older. She can handle a heavier gun. She shoots an 11-87 youth. Advantages are obvious for kids. Reduced recoil. My younger one is very tiny. She shoots an old youth pump. I wish she'd shoot a semi but she can't take carrying it around so she shoots a pump or a 28 ga pigeon I cut down some.
Felt recoil is very obviously a bigger problem for some kids n less in others. Stance and form are critical in lessening the affects of the recoil. So the pump semi thing shoud be figured as to what works best for her not someone else's kid.
If you're up north pm you can let her try a couple.
Cantilever slug barrel? Hmmm lots of guys do this. Bad idea. How far is she gonna be limited to shooting? 30-35 yards? I don't allow my kids to let em fly but that's me but hear me out.
In order to shoot longer distance you do need a slug. This is where things fall apart., to shoot slugs you need practice. Practice w slugs hurts kids. You also need a good rest. Do you find em at every hunting spot?
Now you can use a lead sled while practicing, you can sit in a blind with some sort of cradle but you still need decent chance to pull it off.
Buckshot is what I feel is best for kids. They can practice w light target loads. Only loading buckshot during the hunt. They don't need to know it kicks a tad harder. You can pattern gun n keep it all to yourself. She can hunt with no negative feelings.
I've tried talking to lots of kids missed shots w slugs, tried talking kids back into trying a light 28 after slugs made em decide computer games were less painful,
Up to you bud. Just think bout what I'm saying. Some kids take right to it n some need growing. Don't take a chance of scaring her w slugs just yet if she's young
Check her eyes for dominance before you buy her a gun