As I understand it, these pigments are generally very chemically stable. I had not thought to check at paint mixing places, but I got a set of CMY pigments from Lansco Colors. I followed Nadeau's recommendations as well as I could; Quinacridone Magenta 122, Phthalo Blue 15:3 and Yellow Azo 155 (not sure about this yellow).
The half-tone route does sound appealing for the reasons you state. Are you going to try to turn them at angles to avoid moire or just go for it?
Really looking forward to hearing about your experience with this!