Google these areas and have a look, the West Kootenays is about an 8 to 10 hr drive from Vancouver ( Lower Mainland) in an RV without doing much but driving and refueling. This is not to say you wouldn’t take a few days camping on your way in and out of the Kootenays. So google these places:
Nelson BC, Kootenay Lake, Kootenay Lake Ferry, Kaslo. Paddle wheeler Moyie, Ainsworth Hot Springs, Halsyon Hot Springs, Nukusp Hot Springs, Idaho Peak BC, New Denver BC, New Denver Centennial Park Campground, Silverton BC, McDonald Creek provincial Campground, Summit Lake Provincial Campground, Three Islands Resort ( campground) Syringa Creek Provincial Campground Sandon BC. Nukusp BC, Valhalla Provincial Park, Slocan River , Cody Caves.
All the campgrounds that I listed are on Lakes
Soup