I would make sure you have good cycling bibs, lots of chamois creme, and Vitamin M (ibuprofen). Saddle pain will be your biggest challenge, it will hurt even with good kit. This is one area where you might help yourself right now. You can probably tough the rest out. Ride the hills easy and the rest steady. Do not ride the event hard. Go easy. Take your time. There is nothing you can do to train your body at this point in time but you can make it worse. There is no cramming for an endurance event. Sorry to be so blunt.