I do about the same route all the time, except I come from the S213 instead of the S308. So basically go straigh up North along Line 5 (for example). It sucks to be around the Ming Tombs at the wrong time! Take the G45 on the way back to the city. 220 km, did it on saturday in just over 4 hours. Had to be back for drinks at 15:00 ;)