I'd go so far as to say that Reala and Portra NC are the only color films I'd want to use for studio sessions, nude or not. I've used Reala once, Portra 160 NC a couple times, and Portra 400 a lot, and I've been very, very happy with them.

Fog won't hurt, it just softens the shadows and lets the color gain more dominance over the intensity of the light. For nudes, in fact, I think I'd prefer fog over direct sun (though a heavy fog might make you wish for faster film than Reala -- perhaps you could pick up a Pro-Pack of Portra 400 NC as a backup).