Have crossed on that time ferry many times and as Judy says Les Hautes Coutures at Benouville, which is alongside main Caen road about two miles from port is ideal. Much better than roadside parking. There is a lower parking area which allows you to drive on and pitch without unhitching and it has alectrics. Last year I was the only van there in early September and again in late Sept on my way home.
Site is clearly visible on Google maps and is alongside Caen canal and has access via security gate to towpath for a short walk to Pegasus bridge and the village.
Ian