The optimal location for the triangle piercing is at the natural base of the hood, as high as it can go and still be underneath the nerve bundle (that's where you are going to get maximum stimulation from the jewelry).

Photo above is of a properly placed triangle piercing with custom-bent circular barbell (so the jewelry rests back against the body, which is great for safety and comfort during healing!).

Photo above is of a "biangle" piercing (showing a view of the underside, between the inner labia).

I've been calling this placement a "biangle" instead of a "triangle." When I see women whose spot for a triangle (as high as I can get under their nerve bundle, at the base of the hood) is close to the location where the labia minora divide, I talk to them about their anatomy and explain that the jewelry may be visible right after the piercing, or later, over time.

When the piercing procedure is performed, all of the tissue is compacted together, so there is no way to determine if the piercing will be above this juncture as you piece. Sometimes there's a little bit of space between the jewelry and this location, and I've seen the tissue dissipate over time and the jewelry ends up visible at some point after the piercing was done. 

I used to just say "no" to doing triangles on women with builds like this, but after working with a number of piercers and studio employees and with their consent, trying it out, I've been doing them regularly. Nobody has had any problems whatsoever with healing or any other issues, and the piercings have proven to be as enjoyable as an ordinary triangle piercing. The issue is one of "informed consent" and discussion with the client to be certain they understand and won't be suriprised if they spot the jewelry at this juncture.