This past summer I had reason to travel to Kansas City from my home near DC, so naturally I followed the National Road. One site from Stewart's U.S. 40 which is hard to recognize today is no. 29, "Farm on the National Road", which is located "near Belleville". I cannot be 100% certain that this is it, but it fit the description given in the Vales' U.S. 40 Today as "just west of the town limit and beyond a small new housing development". In any case there didn't seem to be any other place around that could possibly be the place.
A photo from the same angle Stewart used would be impossible due to the increased vegetation. This, if it is indeed the spot, is a head-on view. None of the buildings from Stewart's photo are still there, but I believe the brown garage in my photo is the same as the structure just in front of the pre-fab home in the Vales' picture. That, and possibly the utility pole to the left of the house.