SAsmTOP: you can get two in by putting one into the underwear (SexClothing) line instead of underwear. Beyond that, I'm afraid you're stuck with sharing 65C3 combination files.
I haven't seen a UV map for the skirts, but they're pretty simple things and they follow the old Leg map, more or less. Front centre is in the centre, with right hip on the left and left hip on the right. The top 8 pixels won't appear in a Long skirt texture in use, and I think it's the top 32 of a miniskirt texture that don't show up.
You can't get long coats, cloaks or capes at present, and men still can't wear skirts or kilts. It's my opinion that the wings and skirts should be in a separate directory that
both genders use. Capes could go there too. They'll have to scale for avatar scale anyway, and the backs of the shoulders aren't all that different.
Quick walk-through plus example of layers in use on male torso
here, female waistline vertices marked up and example shown under the grids
here and sicklittlepig's thread still exists
here.