According to this map there was only a primitive road as far north as Chamela and nothing south from Vallarta. I'm sure Tomatlan and El Tuito were there but possibly very difficult to get to. I found this interactive map (link at bottom) years ago on a site that lets you store lots of data free. I snagged the graphics and the web page (HTML) that makes it work thinking the site may go away ... which it did.
This old Pemex map reminds me when Texaco and other gas stations in the US would give away maps free. We always needed them about 1950 as we cruised around eastern Oregon and northern California in the old 1949 Studebaker.
Caminos De Mexico
Aerial view of Melaque - 1955
Full Mexico Map - Caminos De Mexico -1955