So our carpenter is still AWOL, but it's kind of too late in the summer to hire another - they'd be just as backed up as he is and wouldn't get here until October either. October! Our painter decided to come back and paint the actual color over the primer on as much of the house as he could finish. This protects the primer coat, which only lasts for a few months exposed to the elements before it would have to be repainted, and means that we will only have the new shingles unpainted over the winter (which won't hurt them as they are preprimed at the factory). Our painter will probably have to come back next spring to re-prime and paint the new shingles the carpenter puts on in October because, by the time he finishes, the weather will be too cold for the paint.
Anyway, the new color is exactly what I had in my mind that I was searching and searching for and fretting and fretting over, so everything has turned out fine in the end. Whew! I am so relieved. :)