Douglas-fir can be very damp as it is shaded among tall mature trees.
Silver Fir up the road is nicer and a bit more open but also much higher in altitude (~3,000' ASL vs. ~1,000' ASL) but can get cold in summer and closes for the year in early September.
Do not, under any circumstances, go to Cultus Lake.
What? Full of Fraser Valley rednecks and Stanley Cup rioters?
Another option is Porteau Cove PP which just a little north of Horseshoe Bay. It does straddle the shore and the BC Rail tracks so don't stay there if you can't sleep through a rumbling train.