Theres no way to downplay, sugarcoat or waterdown your desires without sounding "too wierd" (which is what you're risking doing anyway).
If I were you, I'd straight up tell her that you have a fetish for this sort of thing and would like to experiment if its alright with her. Theres no way it cannot sound "too weird" so the best thing to do is not doddle or toy around with the idea or make it seem like its less than it really is and just ask her. If she says no or she's not comfortable, then you did the best you could.You could also be proud of the fact that you were honest and didn't downplay your real intentions. And because you were honest with yourself, you won't hold on to the anxiety of not having enough courage to bring this out into the open because you have. There will be no doubt, and you'll be better off and more at peace with yourself.
If you're really scared about what her reaction would be and that it might be negative, I'd ultimately suggest you just keep this portion a fantasy. Whats extreme or crossing the line in another's persons mind is different, person for person even if it may seem benign, cute, or sexy to you.
Its better to save and keep what you have already with her. You've only been dating her for a month. I don't know how deep its gotten in that short ammount of time, so its probably better to hold this off or forego it altogether.
Treasure the relationship, not the fantasies. You'll be glad you did. Maybe later, when you two are closer personally and really start connecting in a deeper and more profound way you could bring this back up to her or wait until then to ask her.
The more trust she has in you the more likely your chances and that she will feel completely comfortable in any of your embraces or affections. Since relationships are, in part, about trust, you cannot undermind this.