more sites (maps from CTC):

http://www.ctc-maps.org.uk/routes/route/558

would appear there is a relatively well-established routing from Calais to southern Belgium...

http://ravel.wallonie.be/_private/r0/ukR0menu1.asp
I love the label: Autonomous Network of Slow Ways...

But as you've already noted, most of these routes seem to move northward from NW France into Belgium rather than eastward across northern France to the Mosel...