James,
The Athearn 45-ft trailer appears to be based on a 96-inch wide Z-Van, while the Micro-Trains 45-ft trailer appears to be based on a 102-inch wide Z-Van.
However, the "road numbers" for the Athearn 45-ft trailers include both 96-inch prototypes and 102-inch prototypes. 
I hear you Carter but that Fruehauf nose bulkhead is SO distinctive. I can live with stand-in paint schemes on a proto that's 6-inches too wide or narrow.
I'd rather have a new, visibly different 45' trailer style (with both new proto and stand-in paint schemes) than a duplicate that "slightly' improves proto fidelity. I don't think N scale is at that point yet, particularly with vehicles or intermodal loads, where we need the overlap.
But stand-in paint schemes on the wrong proto trailer are foobies used to justify bad investment decisions. The scale would have been better served with a different 45' trailer prototype rather than the one that we have had for 30 years, that has arguably the most distinctive features (that nose bulkhead).