Too late for training.
Ride Slow to the 75 mile sag stop and try to have fun.
^^^^^^^This
It is way too late to gain any appreciable fitness before the ride. I would do moderate rides for the next couple of days just to get the ol' legs moving, but wouldn't ride after Wednesday.
Your latest posted strategy of doing the century with cutoff sounds like a wise one.
Listen to your body and have fun!