Unfortunately, the campground our family went to in West Kelowna for a few generations became a condo development a couple years back, so I can't give you advice in that area.
As for attractions on the island, we always find ourselves going back to Coombs, Cathedral Grove, and Tofino/Ucluelet. The road from Port Alberni is two-lane undivided and windy, however, so that might be best left as a day trip in a rental or toad, or a night or two in a hotel. Black Rock Resort in Ucluelet is fantastic.
Further south on the island are Cowichan Bay and Chemainus, which are nice as well.