I've imported a few boats from the US. Every time I've had the transportation company meet me at the Burger King just across the border at Pacific Hwy Crossing. At that point, the haulers remove the plates from the trailer if the originating State even requires plates on trailers (Ma. does not, for example).
There is a large supermarket very close to the BK that has a WA licensing kiosk in it. Buy a temp license there to take the boat from BK up to the border (300M away). My understanding is the the ICBC Binder of Insurance only allows you to take your trailer from the border straight home. Even though the Binder lasts for a few days, you theoretically need to get temp insurance to take your trailer from your home to Canadian Tire for the inspection. The last time I did it, I think I got the RIV form almost immediately, and stopped at CT on the way home. They asked for temp insurance, and I gave them the WA docs.
All in all, it's a very simple process.