I was really upset that I had postponed making our December booking, hoping to get our plane tickets first. I bit the bullet and booked last night through the inntopia link that hawn-yackers posted. (Thank you, hawn-yackers!)
I did a little research first and inntopia is based in Vermont, has been around for a while, and seems to have a good reputation. Most of the info I could find was from people who had used them to book B&Bs.
I think they may have switched to charging for the entire stay upfront, but their refund policy is good. I hope I did the right thing!