It's an absolutely beautiful drive, we call it the Big Sur coast of Mexico.
The bypass around Tecoman is a gift-his directions got us onto it when it opened, and we were so grateful! There are/were great sculptures in the center of both traffic circles.
The comment about a flashy tow, is unfortunately true. Although I haven't heard about anything actually happening on this route for 3 years, we still aren't taking it, sigh.
We LOVE Parador Ecoturistico Zapote de Tizupan beach. Absolutely beautiful, actual hookups, and a wonderful beach. I just looked it up and like you said, it's also called Maruata.
Do take at least 2 days for the drive, if you don't stop to play. If you do, take a long time!