All the discussion in the http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/27785106.cfm tread has been interesting. To me, it all boiled down to sure the truck can handle an over-weight camper ...
Here is the latest info on GVWR in BC. Note the reliance on the Peace officers judgement to use visual clues to determine if the vehicle is unsafe and must be pulled off the road.