I absolutely agree with Don. Our boat rests on the wing when hauled and the stands just keep her from falling over. In our case the rudder is a bit longer than the keel as Catalina started using the shorter C-310 keels on the C-320s but did not change the rudder, so the wing rests on a block on the hard. I would not be concerned about that issue in soft mud though.
I saw a picture posted some time back showing a C-320 sitting, otherwise unsupported, on its wing keel on a hard sand bottom after the tide had gone out. It gave me the willies, but the poster reported that she sailed away with no ill effects when the tide rose again...if it had been me, I'm not sure that I could have survived holding my breath that long...