Ok, I'll persevere with the 700C... but it's starting to seem a little ridiculous how difficult it's been to get it all the way on. I've watched some internet "how-to" videos, and I swear, I'm having a much tougher time than those people in the videos have. It's gotta be at least *partly* because the tire is wicked tight.
Anyway, thanks for your help, everybody.