After the Anzalduas bridge was opened we crossed there in order not to go through Reynosa, we normally stayed at a place close to the bridge in Mission, the Bluebonnet RV Park, cross the bridge and on to Saltillo the first night where we stayed at the Hotel Imperial and then the second night in Matehuala, third night in San Miguel de Allende and finally in to Mexico City.
I would go as far as San Miguel and trough Toluca to Zihuatanejo, I do not know the size of the RV or trailer, the place that we stayed in Saltillo at the Hotel Imperial they have an area for RV's but they have a barrier that swings up, our RV is low enough to pass under, in Matehuala we stayed at the Las Palmas Midway Inn, they have RV parking also, in San Miguel we stayed at the Balneario San Ramon on the outskirts of town.
I hope this helps a little
navegator