Endure the coast route through the city. Yes there is a lot of traffic but I have tried four alternative routes and have gotten lost and pissed-off four times because nothing is marked. Wasted hours and hours of time. Easy does it on the malecon route take your time, ignore blaring horns and swirling buses and taxis.
Please heed Navegator!
Myself I would tend to go Mex 95 and use my San Juan del Rio bypass and go down through Oaxaca and then to the coast. Why?
Between Acapulco and Puerto Escondido, the route is boring as hell. With Oaxaca being a prime destination it tends to overwhelm the Acapulco route.
Once you reach the coast using Oaxaca turn NORTH on 200 to reach Puerto Escondido. This is a quirky town that is not over run with RVs. I love it. There is a tourist pedestrian street just north of the bridge south of town that has a wild myriad number of restaurants mostly Italian.
Going straight across Mexico 200 at the coast junction will bring you to Zipolite beach, which is funkier than hell and a favorite hangout. It's stare at old hippies and grin time. Refer to the Church camping book for specifics.
Heading south past Huatulco TAKE YOUR TIME! The road can have landslides around a blind curve or half the road taken by a cave in. This is no time to rush. Traffic is light.
Salina Cruz is hotter n snot. Summer and winter. Same for Juchitan and Tehuantepec. Hole up using the Church guide for an RV park.
Why hole up here?
You need to depart no later than 7AM the next morning. The isthmus of Tehuantepec has winds left to right so fierce they have a moniker: The Tehuantepecker.
Through the town of Ventana and southward beware of out-of-nowhere gusts to 30 mph. Better than 100 mph gusts in the afternoon. Marvel at all of trees at roadside growing at 45 to 60 degree angles against the wind.
Turn on Mex 190 at Tepanatepec.
Between Tepantepec and Tuxtla Gutierrez is marvelous scenery but the road is narrow, twisty, with several moderate grades. Note the gorgeous pink, salmon with black streaks home roof tiles.
Downtown Tuxtla, keep a sharp lookout for the signed right turn which avoids the forbidden six wheels or or more prohibition. The cops are ultra strict about violations. You want to head for the town of Chiapa del Corzo.
Then comes a long long long uphill grade. The weather is mild here.
I suggest marking your route via Google Satellite and then use street view to help lead you through San Cristobal de Las Casas, my favorite city in Mexico. Mex 190 is referred to as El Bule (el BOO-ley) as it passes through the city.
This is one city where I recommend staying a full two to three weeks. Go to the main plaza by taxi to join a tour to see Chamula and it's National Geographic grade experience. Find someone to lead you to Simojovel a city to the north with a wild west atmosphere buying and selling amber. It is MUCH warmer there so don't overdress. You will go by transport van bus and you definitely need a taxi to find the unmarked open air bus terminal on the north edge of San Cristobal. So much to do. Try the best coffee in Mexico at the cafe LA SELVA.
Above all get a recent copy of the CHURCH BOOK to guide you to RV parks and campsites.
Enjoy.
