Hello Bruce,
I've done this a couple of times and things always seem to be changing. I know when it is done by the person who is the purchaser it is a fairly simple deal, when it is done by someone other than the purchaser it usually becomes a commercial entry. The discretion and powers that customs officers have may seem ridiculous at times but they are protecting our borders and I'd rather deal with an inconvenience rather than a terrorist in our countries.
Here is my advice, because each port director might interpret the rules differently contact the port you will be exporting the vehicle through from this list:
web page
ask what they require at that port for documentation and if you get a burocratic officer that got up on the wrong side of the bed ask for the port director, the fact you are calling in advance is usually appreciated by them.
If you use a broker they will also ask which port you are using or they will fill out every form required and charge you accordingly, although it is not that expensive (less than $500).
I think the above customs website has a list of brokers also.
Good luck.