Yes, I signed up for that tour back in Feb of 2015!
I have a 2011 Ruby with the same gearing as your 2007. I too looked into lowering the gearing and spent a lot of time reading through old threads on this forum. Found that a couple women had success using a sram 12-36t cassette with a new/different derailleur. New chain was added to their setups too. I don't remember the specifics right now. But, it can be done. I was going to go that route and even purchased a 12-36t cassette, but I noticed a nick in the carbon near my head tube. Bike shop checked it out and determined it was just surface damage. I continued to ride it, but won't risk riding it cross country.