Black V dark green/Swedish green .... won’t be that big a difference on a scale model. But it depends on how heavy of a white coat you will use. I make no secret that I add many layers to the base paint to add the perception of depth. Many believe models should be painted in the same way the real vehicle is painted. In this case, Black would work ... in fact any colour work or no color at all ... if the white is heavy enough. These same people do not believe in using affects to add depth, and weather directly on top of a flat paint coat. Personally I think this looks terrible. A 1/35 scale model does not cast shadows and reflect light in the same way the real thing does, and needs some technique to add the depth first.
I paint using layers to build up the depth, and like a darker colour underneath to do so .... a pre-shading technique. In this case, I would opt dark green more than black, and use more translucent layers of white. I also use some drybrushing on protruding edges and pin washes in recesses to add this depth. I have never used modulation as I haven’t finished a model since this become trendy. I could imagine using a subdued version of this as well. The techniques however should not be clearly visible on finished model (my personal opinion) .... they should be toned down with filters, washes and weathering to give a natural finish.
When I say white, pure white should only be used in highlighted areas. Painting pure white on a scale model with no depth would look terrible, in my opinion. White on top of silver would probably be the right options on a civilian aircraft ... as a satin clean finish is the goal. Panzers, not so much. As I paint with mostly with the airbrush, I can change the hue of white, and can do this easily. From an aerosol can, its a whole different method. I used to paint models in this way, and found it limiting, buts its long from impossible. With the airbrush you can change the hues while painting and even change the hues to be closer to white with the last stages. With an aerosol white, it would be important to mist on the paint so some of the under-colour comes through to give the illusion of depth. The hue can then be changed/toned down with filters and weathering.
I have checked out images of the white UN CV90s and the wheels appear to be left in this green colour while the rest is painted white. So it looks like you will have to use green anyway. I have seen others with white wheels so it appears to be different standards? Anybody have info on this? I would opt for green wheels option to add some interest and contrast to the finished model, unless following a particular scheme/reference.
It must also be remembered that this is my own thoughts on the subject and from experience of building panzers. I can understand that painting white as in the original question there are many answers. My answer is no more correct the F Porsche´s, depending on any one individuals own preferences. I can only recommend.