Late return ferries

Hi,  I would appreciate anyone's advice /experiences about where to find a pitch for the night when the return ferry docks at 21:45.  I went Poole to Cherbourg earlier in the year and am doing the same next month.  Last time I tried driving but had to pull over in a quiet lay-by and carried on at dawn.  Anyone have better suggestions? Would club site wardens blow a fuse if I pulled into the late arrivals space and left early?