You can try this BC Government website. It has all of the Recreation Sites (camping) on it in the province.
Most are accessed via logging roads and/or trails but if trails they likely are hike-in only.
http://www.sitesandtrailsbc.ca/
Some of the guys in the Coastal Cruisers Toyota club run these maps:
BC Backroad GPS Maps by Backroad Mapbooks published by
Thanks to my buddy, Rob S for these sources