I'm not sure the rules of the ride, but another option might be to ride some of the days (shorter days, better weather days, etc), or some of the distance each of the days, and SAG the other days/remainder of the distance. You still need to face the group riding issues and there's still risks, but you might be able to enjoy parts of it.

I would expect to be less tolerant of conditions and varying terrain, and possibly pretty tired. You never know until you get closer, though. You might be able to transfer your registration, though that doesn't save you the travel costs.