Perhaps not for the CWBP, but I could see a joint venture under the publisher name and copyright of "Cartographers' Guild" where a controlled collaboration of CG members create map, map tiles, map objects, illustrations and/or adventure products made available at DTRPG under "pay as you want" where all proceeds go to the support the Cartographers' Guild website. If material is not designed for a specific game system (like for Pathfinder, for example), rather 'fluff' material only and game system agnostic - there would be no need for OGL or other licensing concerns. While it could still be a CC derivative license, I don't think using a CC license would be necessarily the best recourse, a fully licensed to the CG might be the way to go. Under 'pay as you want', buyers can pay nothing and download for free, but have the opportunity to contribute if they want (and RPG gamers do pay small amounts for this material).

That way the concern of some third party stealing the material for their own publication would have considerable more protections provided towards the Cartgraphers' Guild's ownership of said material.