As mentioned, Skyranch is not Santee. It should have its own zip code as its in the hills with a terrific view. You must not have lived here for very long. Are you from back East?
BG has some excellent points regarding south county. Check them out. Another local hidden spot is called Elfin Forest. In the hills between Escondido and RSF. Some jewels in there.
You have pretty much have called out the only other acceptable spots in SD. I would look near the border. It might be more of a drive than you would like but doesn’t have the issues you have already discussed. Good Luck. Good news is interest rates should remain low for a while.