M20 closed coast bound for cars/vans/local traffic

I understand at the moment they only have the M20 Coast bound carrigeway between junction 8 and 9 to stack HGVs waiting for the tunnel or ferry, and thats fair enough, a massive lorry park is never going to be built, as no one will want that on their doorstep.

However the other cariageway should always remain open to cars/vans/local traffic, with 2 lanes for each direction, even if its 50mph. Not sure how this would work at junction 8, separting French bound HGVs, and cars/local traffic, but maybe a second on/off slip road just for this purpose at junction 8 is the answer.