PEB,
Welcome to Summerland!
As for water and camping, I'll ask around. There's plenty of places to bush camp; just drive into the hills and call a patch of dirt home for a spell. If it's not Native land no one will bother you. Plenty of down/dried wood to burn (which also means to be careful of any fire you build). Unfortunately, water is always an issue. I can't think of any sources of water which I'd want to drink from. The issues are run-off and dirt/silt and cows. I don't think it's safe or worth the risk.
If you're going to bush camp it I'd suggust that you pack your own water.
I'd offer you and your buds my place, but I've got the whole famn damily coming here that weekend too.
In which areas in Summerland are you going to ride? The farther out of town you go, the better the trails.
That being said, the farther out of town you go, the greater the gain in elevation and the risk of snow (still, a pretty low risk unless you want to go into the mountains).
Other popular networks in the area are in Peachland and Naramata (both within a 30 minute drive of Summerland).
Pray for rain the day before you arrive. Or bring lots of Filter Skins.
And soften your front end in anticipation of the rocks; a good crop has grown over the winter.