There are couple of good web sites out there for the import requirements… make sure you cover your customers bases as well, or they will get hit with several hundred dollars or more of unexpected fees.

Here are some sites that should help:

Start with the Canadian Registrar of Imported Vehicles http://www.riv.ca

RV specific answers are here http://r-pod-camper.blogspot.com/2009/01/note-to-our-canadian-r-pod-customers.html

Lastly, make sure you handle all the paperwork you can for the customer, you can deliver to the border and they will take possession there – if any fees or paperwork is not done, the exchange will get hung up.