If by "detail texture" you mean "decals," a guy over on Discord informed that adding a "1% opacity fill layer" underneath his texture fixed the decal bleed through issue.
Are you sure vertex alpha is not related to snow/ice? If I place quotes around the term "detail texture," which eliminates all hits but that exact phrase, the only hit at all refers to "detail surface texture" on scenery polygons. If I search "detail texture vertex" without quotes and select the "ice" hit, I get this "For the actual ice texture and material, you'd use the vertex paint modifier to paint on the vertex alpha." Please confirm.