I thought I saw an elevation profile somewhere for this ride, but I can't find it now.

The ride is designed so that the 24 and 46 mile rides follow the same route, and then just as the 24 milers are almost finished and turn left to go back to the start, the 46 milers go right and keep riding. So you could start the ride planning to do 46 and then decide to cut it short if you're not feeling well. There's also good SAG support, just in case.

As for how hilly is it - it's not flat like a ride on the Eastern shore and there are a few good climbs, but overall it's not that bad. It's definitely not as hard as the Philly Livestrong ride.