Ive never seen a single one in all the years we have been motorhoming apart from the time we visited the Jungle by accident on the scooter.
As Allah is my witness, and not to make any kind of a point just observations, in the last couple of years ie since the grande Calais migrant clearout I've seen just a handful of migrants on the outskirts of Calais, limited to the major roads.
But in most previous years I've witnessed a few dozens mainly in Cite Europe M/H parking area (domiciled in the adjacent tree copse), one time a couple of half hearted attempts at breaking into a caravan and a motorhome, and on the major roads, at the ferry terminal itself, attempting (and with some success) at breaking in to curtainsiders.
About 6 or 8 years? ago there were 150 to 200 occupied tents squeezed to on a grassed area on the road approach from Calais Centreville just before the Ferry Terminal itself. Portacabin bogs and charity canteens nearby saw possibly hundreds. Lasted maybe 2 or 3 years before being cleared.
That's the rough extent of my experience based on 2 or 3 overnights in November and 2 or 3 nights March
every year since sometime in the last century, just to give things some context.
Why 2 or 3 nights....friends nearby.
Jack Straw went to Dover for a photo shoot back in the day. The first truck door he opened produced
a migrant, remember that? He obviously was luckier than you! Point is, generalisations cannot be made
from limited number of experiences.