>  We will go to La Paz  and
>cross the ferry to Mazitlan then down to Puerto Escondidio.

In Puerto Vallarta there is a great place to park/camp right in the
center of the "old town".  Hotel Frankfurt is a hotel/restaurant with
small enclosed camping area in the back.  Hot showers, flush toilets
and a short walk to the beach.  While it's not as nice as camping "on
the beach", you can stay in town and walk everywhere.  Old town PV is
the nicest of the big Mexican resort towns.

http://www.pauldottrip.com/puebla_pv/pages/DSCN2105a.htm
http://www.pauldottrip.com/puebla_pv/pages/DSCN2106.htm

If you have the time, you may want to consider driving east in Mexico
and seeing some ruins like in Palenque.
http://www.pauldottrip.com/palenque/index.htm

 From there drive to Merida and take the Yucatan Express Ferry to
Florida and drive up I95 to Canada....but check if the Ferry is
running....it may not be running this season.
http://www.yucatanexpress.com/