I asked the locals in Lee Vining about sailing Mono Lake and they said, "Go for it!" I don't know about a launch ramp, but I think there's one in town, so bring beach wheels in case you need to beach launch. I don't know where to find a wash down, but the salts shouldn't hurt the boat too badly, besides, you can rinse it off at any other fresh water lake such as Crowley Lake about an hour south, or Lake Tahoe.
All types of boating are permitted on Mono Lake, although access is restricted to all islands between April 1 and August 1 each year to protect the nesting gulls. It is advisable to stay near shore while boating, and to be alert for sudden high winds. We recommend launching canoes and kayaks at Navy Beach, on the south shore, where a parking lot is close to the water. For those with boats too large to carry, an unimproved launch ramp is available near Lee Vining Creek. Stop by the Scenic Area Visitor Center for directions.