We have been using equal parts of 70% Isopropyl and water mix with a little vinegar to yield a homemade glass cleaning solution. The recipe is typically 1 cup alcohol/water to 1 Tbsp vinegar.
Would it work as deicer? Yes. Would it be better than using either alone? Probably not.
Cause the idea of mixing either alcohol or vinegar with water is due to their low freezing point, which they could slip in under the frozen ice and hence de-ice. There will be no harm as far as combining the two together since there will be no fume or dangerous chemical/gas release.
If you want to try, might have to adjust and twist the recipe around