You should check Martin's fan art policy, if he has one. Most authors exercise voluntary ignorance toward matters of non-commercial fan art, although there are a few who outright disallow it and at least a couple who permit it under certain conditions.

If it's the style you're most interested in, you could probably look to see if one of Pasis' maps carries a Creative Commons license that permits derivative work. He was the one who developed that style.

As for the moderation thing, you're the second person today who's mentioned having a post caught in the mod queue. Maybe the community leaders need to be prodded about that. Hopefully there wasn't some bug in the forum that ate them…