We also received a phone call from GCE alerting us to the cancellation of the reservation.
I, unfortunately, found this out only 4 days before our departure. When I called the Bike Barn there were no carts to be had, of course.
I was really fuming and ended up talking to the recreation director for FW and WL. She assured me that they had ordered many more carts and that they would be on-site by the time we arrived (this was the weekend prior to Thanksgiving).
She even had the cart delivered to the Reception/Check-In since we weren't arriving in time to get to the Bike Barn before it closed....
I think you'll be okay!