Maybe an approach like in Illustrator could be a good idea: you set the document's global color space to _either_ RGB _or_ CMYK, with no possibilitiy of mixing the two modes later. In XX, there is no "hand-holding" regarding color space, and all kinds of mixes seem possible -- which will in most cases result in problems later in the workflow. I cannot count all the times I have _thought_ I defined nothing but CMYK colors, but some little RGB bastard was stuck in there nevertheless.