Pretty sure that my first exposure to Mexico will be the caravan offered by La Penita RV Park, if they still offer it once I retire in 12 years. For the price, which is one month of staying in the park, it's essentially free and would bring me to the area I'd really like to visit on the way there (Mazatlan). Stay in their park for at least a month, visit Puerto Vaillarta, head to Mazatlan and check it out longer than a stop over and then tag along if they offer a caravan back.
Show me the ropes once and I'll be able to handle it on my own from there.