If you are headed for Puerto Penasco or Rocky Point, one route to take is to head to Lukeville, AZ. Off I-8 turn off at Gila Bend and head straight south on Az 85and pass through Lukeville to Sonoyta, Sonora (the Mexican border point) for heading to Rocky Point. Head south west on MX 8. If heading SE, you are going towards Santa Anna so you're on the wrong road, it will take you eventually into Mainland Pacific Mexico. If you think you might do that, you will need to get a 10-year pass and sticker for your motor home, and import (temperarily) your towed vehicle, and post a deposit on it with a credit card, either 200.00/400.00/ or 600.00 depending on its age. Once you pass through the border going north, you will get that deposit back onto your card in a few hours.
But in the Hassel-free Zone, that does not apply. You will only need to get, and pay for, a tourist pass, the FFM, and buy a ten year pass for your motor home, but wait - not sure about that!for the Hassel free zone. This will allow it to enter without further payment if you plan to enter again with the same motor home. (If you plan to sell it, or even if there is that possibility, be sure to turn your 10 year permit in at the time you leave Mexico.) And of course, present your Passport.
The Andrade, USA crossing is next to Los Algodonas, Mexico, the signage you will see from I-8. It may be the shorter way, and can be congested at times. But it also opens the possibility to visit San Felipe, Baja (hooking up to #5) or checking out Gulfo de Santa clara on the Sea of Cortes, or bypassing it to travel through the Altar Dessert, to get to Rocky Point. Highway 2 in the north will also get you to Sonoyta, then turn south on 8 for Rocky Point, all these roads are in Mexico. I liked the road through the Desert!
Go online to get your insurance. You may be entitle to a rebate during the time in Mexico when Your Canadian insurance is null and void. You will need verification to place you in Mexico for the isurance companies.I concur with Moisheh that Lewis and Lewis is a good broker for Mexican insurance.