Thanks for answering.
When it looked like noone was going to post an answer to my thread, I contacted Andy Warne who sells the AVGA. He was so kind to e-mail me back saying that he was almost certain that what I was hoping to do would not work. He hadn't tried it but he figured that "Powerstrip would have a problem with the differently-calculated dot clock and would in fact set the dot clock to the wrong frequency".
So, I'm still a little confused. Have you actually created one of my wanted resolutions and can confirm that it actually does work?