Dont worry about pinching the line or running the tank dry. There is sufficent residual lube in the engine to protect from direct metal to metal damage. In order for an engine to be damaged by metal to metal damage from lack of lube, the engine must countine to actually run for a significant amount or time after the fuel is gone! And as we all know, when the engine runs out of fuel, it is only a matter of seconds before the engine simply shuts itself down.