After months of experiments I finally found clear coat which would not affect Alclad paint's shades - Gunze acrylic clear gloss (H30). I've painted couple aero elements in Alclad Stainless Steel and sprayed H30 over. I initially felt that Alclad Polished Aluminium shade was too bright. After I compared SS and PA shades, though, I realized that SS is too dark. So my final choice is Alclad PA. And the fact that PA shade is not affected much by Zero 2K clear coat is great too.
Here is picture of MP4/22's body with Alclad PA on it, but before clear coat. There is a problem with it - every smallest blemish in base coats shows up. I'm really not looking forward to starting all over again, but not sure I could live with current quality either. We'll see how it'll look after clear coat is on.