Suggestion, borrowed from the stripper deck I got last year:
On each card, the artist's name. Make it print or signature, doesn't matter - whatever the artist wants, can even be a handle/signature/glyph or whatever else you use to sign your work.
Back - simple, tasteful pattern. It makes the cards more playable/useable. We want the focus on the front, and an elegant, classy back that doesn't steal focus from the front art.
One ad card - AetherCards; Alex's standard card.
The other ad card - THAT'S where you put all the names for credit. Autographs if you like, print, both, whatever. Use both sides of the card. No symmetry issues because it's an ad card, never gets played. If more space is needed, maybe Alex would permit the back of his ad card to have "page 3" of the credits.