I travel the freeway from Calgary/Las Vegas/Pheonix/Nogales usually a couple of times a year. Freeway all the way then toll freeway all the way to Manzanillo.
Stay on it. There are hotels and fuel stops. Hide your cash on your body. Only keep enough in your pockets for tolls, fuel and food/hotel. The military stops (I was searched early July 2024 three places between Nogales and Tepic) Always looking for cash, drugs and ammunition in that order. Somehow got a few thousand off me while counting in front on me.
Stick to toll freeway 15D and you'll be safe as it now bypasses most big citys. A few sharp corners to watch for but the road is not bad