Not sure I have seen that on Shasta, but there are a few options on the Delta. Get in contact with some Real estate agents in Disco Bay. We rented a couple of different private homes in Disco bay over the course of 7-8 years for summer trips. Probably the best WS trips I ever had, including houseboat trips, especially with a large family type group.
We go to Tahoe every summer as well, I have gone since I was a kid (30+ years) I never did consider tahoe a water ski lake, though I do see a lot of ski boats on the lake, I just can't imagine.
The last couple times we hit shast the crowds have been a bit of a factor, could have just been where we were, but so far, from what I have seen, the delta gives you the best opportunity to find an uncrowded spot and water so consistantly flat you can barefoot all afternoon.