Sounds like you're familiar with the summer zoo around Kelowna! Vernon area is busier than it used to be, but still not as crazy as Kelowna. Some folks like the excitement, but I prefer it a bit more on the quiet side. Used to enjoy motorhome/trailer vacations too, but not so much anymore. A tent at a remote lake is more appealing these days. Most of the Okanagan gets busy in the summer as you know, but half hour in any direction from Kelowna, especially into the surrounding hills & plateaus, things quiet down substantially.
Anyhow, I'll throw one more option out there for you, if you don't wish to haul a trailer behind a gas guzzler. The Illahee Inn on Kalamalka Lake.
http://www.illahee.com/
A bit on the pricey side, not cabins, more of a lodge atmosphere, bed & breakfast. Includes some nice extras that you wouldn't get with a cabin rental. Even though it's located in Coldstream, part of the Greater Vernon area, it's actually a very quiet location since it's close to Kal Lake provincial park. You'll have to do the math, but by the time you calculate your fuel bill for hauling a trailer all the way from Calgary & back, the end result may not be all that different & your carbon footprint will be much lower. Downside is that your daily drive to Carr's Landing will be a bit longer. Shouldn't be too bad though, if you take Commonage Road past Predator Ridge, the drive shouldn't be more than 30 mins.