Is there a reason to suspect that tackling both of these at the same time (e.g., demographic specific initiatives) yields significant benefit over alternatives?

If you treat a field as gendered in your recruiting of kids, the sum of your efforts may ultimately balance the scales more than they're self-defeating. But don't think for a moment kids are stupid enough to hear a gender-specific, or gender-targeted introduction/recruitment to some field and not walk away with some notion that a field is "for" a specific gender, or that one is "better" at it than another.