As noted by several, you really should have a 2006 or earlier diesel. We have a 50 gallon Transfer-Flow which really makes for peace of mind. We have been to Baja once and Yucatan three times (last time to Belize an Tikal). Most of the US and Canadians we know in Yucatan spend their nights going down at all night Pemex stations. They can be quite safe - and there are just not many RV parks south of San Miguel anymore.
Extra fuel filters are a good idea as noted but every medium and larger city has accredited Ford/Chevie/Dodge dealerships.
\\extra tries for 5th wheel or trailer is not a bad idea. One can get truck
tires in any large city but RV trailer tires may not be readily available.
Glad to finally find something on line concerning Mexico travel
Reed and Elaine