To follow up I think you could combine the Airplane Field 35 mile ride with the Kingston Springs 62 mile route. Towards the end of the Airplane Field 35 ride you hit the Natchez Trace Parkway and pass the Mile 440 parking lot where the Kingston Springs route begins. You could then follow that route, return to the 440 mile parking lot and then ride the conclusion of the Airplane Field 35 mile ride back to your car. You should come close to 100 miles that way.