I did a quick scout around croix de guerre. There's one scenario that requires nine Opel Blitzes. Otherwise it looks as if the reason for having 46 (there are 46; I counted them) new Opel Blitzes (and 24 wagons and more and more soft halftracks) is the CG. Nearly all the Gun RGs include a truck (/wagon for the French) for each Gun, and the rafts come on trucks, and there is a transport section that has nine Blitzes. So it's possible you might need 52 (including the six original) Blitzes. It looks like you're going to need those MP SMC counters after all.
The odd thing is that there is one scenario with nine Buessing NAGs (the heavy truck) plus a fair number show up in the CG yet I don't see any extras on the counter sheets.