Any vehicle over 10,000 pounds (registered weight), or vehicles pulling trailers are restricted from the left lane where posted. To throw a wrech in the cogs, I have read in the Seattle P-I in the traffic issues column that the state patrol public relations officer in Seattle encourages "RV's to use the carpool lanes if there are 2 or more peaple in the vehicle!!! Wich is a direct contradiction of the rules as posted. As far as passing the left lane rule is only in posted areas and there will always be at least two lanes in your direction of trave to use, so you can still pass grandma Mike!
The speed limit I was not aware of and the rules are not the same for you in your pickup with a trailer as they are for the "big rigs", Most of my experience with the differences is with over dimensional (wide or high) boats, In a non -commercial setting the rules and permits are vastly different. One other thing to keep in mind is just because a trooper / commercial vehicle enforcement officer writes you a ticket for something does not always mean he is #1 correct and #2 following proper procedures. My company fights every ticket our drivers get and a majority are thrown out, we pay fines on maybe 30% of non weight infractions, and a majority of those are reduced fines...
Oh and Sinker That may well have been a bbq, they do that from time to time for public relations. Usually have pretty good food too...