We did it for our previous Class C that we bought from a rental agency in BC. We used a Customs Broker to handle the paperwork, and were able to drive it thru the border at the Truck Route crossing and did not need to go "inside" for more complex paperwork.
We needed a USDOT compliance certificate from the manufacturer. (In our case for a Triple E RV manufactured in Canada). Also any RV sold in Canada requires a propane system inspection and certificate that shows compliance. We paid the dealer about $1,000 USD to replace the tires, replace the batteries, change the speedometer/odometer from Kilometers to Miles, and to do the border crossing paperwork.
The broker drove the MH to (and thru) the border with me, which allowed us to avoid GST tax issues, that would have required us to pay the tax, and then apply for a refund. It was a very easy experience. I think that the GST situation is much different now.
2008 Itasca SunCruiser 35L
2014 Honda AWD CR-V EX-L