Camaïeu

LuLu, I have a wonderful new word for you: Camaïeu -- from Wikipedia, it's "a technique that employs two or three tints of a single color, other than gray, to creat a monochromatic image with out regard to local or realistic color.... This French word once was synonymous with cameo..." I think this perfectly describes your challenge: the dozens of shades you'll be using to produce an overall effect of four simple colors, background gray-but-not-gray, red, cream and blue. Now if only someone would tell me how to pronounce it...