As you can see in the screenshot, The thighs of this woman have no poke through in the iClone 8 viewfinder. There is indeed poke through, but I have the opacity on her legs set to zero. Yes, I do see the problem in her shoulders too.
Let me head you off at the pass now: Conform doesn't help. Loose fitting and increased size doesn't help, and her bodysuit starts to bunch up when I try it. Yes, I also see her toenails poking through
The thing is, I can get around this for extreme poses with selective key framed opacity. It works fine for a native render, but nothing makes any part of her skin go  invisible in IRAY

On the left, we have a boring native render. On the right, we have Iray with her totally clear skin clearly showing through her bodysuit.

I've made the entire opacity map black. I've even deleted the diffuses texture. That just leaves a gray poke through.

On the Iray materials side, I've selected her legs and reduced the opacity. Nothing. The only thing I can think of is maybe a clear iray shader (if that exists.).

 Besides changing her outfit, is there any way to get Iray to respect opacity when conform fails?

20% of original size (was 2560x1440) - Click to enlarge