When it comes to the modesty debate I think we focus a bit too much on how women's clothing can be an occasion of sin to men. I don't mean that in the ridiculous "victim shaming" way that feminists do. It is a factor and women should be aware of it. We need to do our part and have compassion on the weaknesses of our men. But there are two reasons why it might be less effective as the primary argument:
1) Girls don't really understand it. I mean, I knew theoretically, I had been told and believed it, but I didn't really know the breadth of temptations for men until I was married a few years. Now I know and in fact we just joked the other day that I could be wearing trash bags and my husband still couldn't resist me. But before marriage this concept was very vague, which is ok. Give too many details and you risk ruining innocence, ironically while trying to preserve it, which would not be good either. So it's better that they don't really know anyway.
2) Women are generally schizophrenic on this issue. Modesty is something that touches to our very core and the desire to be wanted or noticed is as powerful and intoxicating as a man's "desires". Eve pre-fallen-nature must have been breathtaking. But this wanting to be wanted thing is out of control post-original-sin. So as much the "temptation to men" is a good argument we just won't listen to sense. Women will spend hours shopping and trying on clothes that make them look and feel sexy but dare point this out in the context of immodesty and they will deny, deny, deny. It is a mindboggling, and often wilfull, blindspot. A girl can post a pic of how sexy she feels in a little black dress one minute, but then get extremely offended the next minute if it is pointed out that women dress provocatively on purpose. People openly talk about the sexiness of high heels ALL THE TIME, but point it out in the context of immodesty and the desire to elicit lustful feelings and again it's offense and denials. The first thing women do when they try on a pair of skinny jeans is make sure their backside looks great, but point out that jeans are worn with the intention of turning heads (in most cases) and all hell breaks loose, almost literally. It's insane.
This happens all day long in the trad world too, to all different degrees. They aren't just talking about wanting to be pretty. They are fully seeking to be sexy and attract (which all adults know translates to getting attention and arousing lust) and will admit it in every other context except in the immodesty discussion. Only then do they walk it back and get their feelings so "hurt" because all they want is to be "pretty". The duplicity or blindness or cognitive dissonance, whatever you want to call it, is out of this world. It's a brick wall so thick nothing but a miraculous amount of grace and humility can get through it.
Some random "creepy" guy confronting them would only send them deeper into denial. If some random "creepy" guy confronts someone, he is basically admitting he is tempted by her and that gives her a weird twisted kind of power over him. So she can turn the tables on him, write him off and avoid facing whether he spoke truth or not. Because he is a creep, right? Who does that? She does not have to listen to weirdos. She will fight tooth and nail to make it about him and it's just an all around bad road to go down. Better to leave it to the fathers and priests from the pulpit. If they don't deal with it, they will answer to God and it won't be pretty, don't worry.
There is another side of the argument that I think might be more important in the formation of young girls and that is to teach them why modesty is best for their own salvation and their own souls. Not only does it attract the right kind of man and win them the right kind of love, but it seems like modesty is the first battleground for a woman's soul. I do not have saints writings to fall back on but if my observations have any grain of truth to them, the interior disposition necessary to dress modestly seems to be essential to striving for any real degree of sanctity. The interior grace, the humility, the docility, the ability to take a brutally honest look at oneself and one's deepest motivations, the ability to take correction, the ability to face and accept (with humility) the embarrassing feelings of having crossed the line, the ability to repent and turn that embarrassment into a resolution not to sin again, the fortitude to stand out as a little different, the internal serenity or confidence of needing only God's approval (as opposed to the lustful approval of hundreds of men or the jealousy/approval of women, or even one's own admiring approval), the mortification of vanity, the perseverance to make the right choice even if it's inconvenient, the ability to look past the current cultural norms to see if there are absolute human truths, all of those virtues (and more!) factor into this one decision of how to dress. How is a girl or woman going to reach any serious degree of sanctity if she can't even practice these virtues in something as basic as what clothes to wear?
That's not necessarily a call to judge the state of each woman's soul according to her clothes, we are all in different places along the journey and only God knows all the details; but it's meant more as an observation for each girl and woman to make about herself. If each girl understands that the virtues she practices in something as simple as clothing have far-reaching effects on everything else in her life, she might be more inclined to take it more seriously. Modesty is so closely intertwined with humility, without which all other virtues will be stunted. Sure, we can push the envelope and still end up being nice girls and generally good women, but will we be saints? If we learn to spot this weakness in ourselves and work hard to eradicate it, we might have a fighting chance. It at least tells God we are serious about cooperating with His grace in all things. I think impressing upon the girls why modesty is so important to them and why modesty is so good for them might help many of them muster up more conviction when faced with the over-powering temptations to dress immodestly.