You can fly into Tucson, rent a car and cross border at exit 4 melposa exit truck route. Do not go downtown Nogales. Be sure to get your visa at Mile marker 21. The visa is free if you stay 7 days. More than that it is like 20.00 US dollars each. Just follow all signs to Guaymas through Hermosillo.

4 lane Hwy road from border to San Carlos except through Hermosillo. This is a toll road, 3 tolls with a total of approx 16.00 dollars. First is at Nogales, give 20.00 US and you with get pesos returned.