Hi! I'm new to the board and biking but I've lived in Cumberland (the area anyway) my whole life. The trail is amazing and the canal is great too. We have a business off the canal and our home is off what we hope to become an addition to the rail trail.
You might be able to rent a SUV from Enterprise in Cumberland and leave it at an Enterprise in Pittsburgh. This is done occasionally for our auto customers at our business. I think we also have a Hertz rental but it's slightly more expensive. When you do come to Cumberland, I hope you enjoy our town!