About planning your route, give your husband this link to the SCT website, Mexico's dept. of transportation.
Rutas Punto a Punto
Input a starting city, ending city, and up to 2 intermediate points, and you'll get a route, driving distances, driving times and tolls. In case your Spanish isn't up to snuff, Estado Origen means Originating State. Estado Destino means Destination State. Ciudad means City. To include intermediate points, click by where it says 'Si requiere agregar puntos intermedios en la ruta'.
Make sure to pad the driving times it gives you though. Unless you are very familiar with the route and do not hit much traffic, you'll find SCT's estimates quite optimistic.
I also recommend that you get a
Guia Roji atlas. In my experience, they are the most accurate. Ours was invaluable.