We had our boat trucked from Alameda, CA to Tacoma, WA, in 1998. The company who did the job, Associated, used a special trailer that drops the forefoot of the boat almost to the pavement to provide maximum bridge clearance. I have seen boats way bigger than ours come into the Seaview North yard in Bellingham on trailers. GB42 and 46, Krogen 42s, and sailboats up to 60' long.
Associated told us that a GB36 is the largest GB that can be trucked on the west coast without removing the flying bridge. Back east, they said, even a GB36 usually has to have the flying bridge removed because of the lower clearances of the older overpasses and bridges back there. It depends on the route, of course, but they said they almost always have to remove the flying bridges on boats they truck from here back east. This adds considerably to the time and expense of the job.
In 1998 it cost right around $4,000 to truck our boat up to Tacoma. Hiring a delivery skipper would have cost the same amount and our insurance company was WAY happier with the boat on a trailer instead of out off the coast. Also, the truck journey took only three days including load and unload time. A broker friend bought a GB46 out of the same marina in Alameda a couple of years ago and the ferry trip up the coast took almost two months due to bad weather.