Thanks for coming back and sharing, Pete. I ended up getting an ITIN. I found an IRS acceptance agent here where I live (I hadn't even heard of acceptance agents but I stumbled on the term looking on the IRS site) so it made things much quicker. They were able to confirm my identification for the IRS (so i didnt have to worry about certified copies) and do all the paperwork. He suggested we file a tax return as they automatically assign the ITIN when you do that, and I didn't have funds withheld by my publisher or agent. That also meant I didn't need a letter from my publisher. (My agent had requested one but they said to use my contract, according to the acceptance agent recent criteria changes have made that unacceptable) I got the ITIN in the mail in about 3 or 4 weeks, during tax season, which was much faster than I had expected. For the tax return and ITIN it cost $300, which is a lot, but can be written off as an expense. But it was worth it for me.
Just thought this might help others going though the process.