Thanks. I already tryed most of the mentioned tasks ... but I hoped, there is an "easy" way.
Actually, there may be an "easy" cheat around this. And, I'm not talking about normal maps and painted pubes, though, depending on he scene these could be all you need.
Like Jumbi said, there's the push modifier, and you can work on what becomes the collision item for the clothing in question, and, then, there's dForce, that you can use (unless I'm wrong, the monokini in that particular render is a dForce outfit). But, in either case, there's a problem, if the pubes have geometry. Fibermesh hair, which is what most pubes use for geometry, are neither push or dForce friendly, they will easily distort the clothes, or turn the dForce simulation into an exploding mess. That much we all know, and, if not all of us, most of us had to suffer through that, at one time or another... BUT! there is a little cheat you can use, assumming you will use either collision smoothing, or dForce, and, that would be an old trick, one that I used to use a lot back in Poser, and its dynamic cloth simulations.
This first set is exclusive for dForce
1) Load your base figure, and set the timeline FPS from 30 to 60.
2) Got to frame 15, and shape the base figure, add any geoshells you need, i.e. anatomical elements, golden palace, newgens, fender blender, breastacular, etcetera, and, of course, apply textures and use the scripted "mat copy" function on whichever geoshell needs it. Also, add the pubes.
3) go to frame 35, or 40, and pose the figure, at whatever pose you had in mind. Then move backwards in the timeline, at 5 frame intervals, to check if the limbs cross through the body, or otherwise would ruin the simulation plan. If so, adjust the limbs accordingly, to avoid that
4)Return to frame 15, and load a basic primitive. I suggest a shpere, or cylinder, ideally a sphere. Then move it so that it sinks into the figure's groin, and shape/torture the primitive, so that is only covers the pubes geometry. Take care that it won't create hard sharp edge angles around it (hence the sphere), and that it barely covers the pubes. Ideally, you should be able to just view the very edge point tips of the pubes trying to poke through the primitive. Parent the primitive to the figure, making sure it's "parented in place", and backtrack, again in five frames intervals, to make sure it doesn't go out of its designated spot. Once you're happy with that, return to frame zero, select the figure, load the dforce clothing piece, add whichever simulation settings that may come with the outfit, and run the simulation. If you did everything perfectly, you can simply turn the primitive invisible in render, and just render your scene. You should have a pretty convincing result with no hassle with explosions or pokethroughs.
And, now, the less roundabout version of the same for collisions. Just load the figure, shape, add geoshells, textures, pubes, the primitive, shape and move it just like the dforce, load the cloth, work with the collision and smoothing values to finetune things, turn the primitive invisible to render, and render.