RE: recovery craft
If I had done that, there would have been water inside which would have rushed to the tail with the acceleration of takeoff, thereby making it vastly tailheavy and it would have had a very short flight to the site of a lot of splinters floating in the lake.
Once it's on its back, bring it in, remove the wing, and make sure the plane is dry inside. I'm glad your friend was lucky. I would rather be lucky than good anytime.