Sorted by proximity to the Kelowna Yacht Club.

Hiawatha RV Park: 1-888-RV4-PARK
http://hiawatharvpark.com/
4.9km from the yacht club.
Approx $55/night for full hookup.

Bear Creek Provincial Park: 1-800-689-9025 (Discover Camping BC)
http://www.env.gov.bc.ca/bcparks/explore/parkpgs/bear_crk/
11km from the yacht club.
This is a very popular park so I would advise booking as early as possible, which is 4 months ahead of your arrival date (May 10th probably).