I too install and remove the rudder on my M15 while the boat is in the water.  Never had a problem. 

 

I recently returned from another sailing trip to the Fall River and Big Lake in North Eastern California.  Steady afternoon winds. Sail amongst the trout fishermen and their guide boats seeking trophies along miles of meandering spring fed rivers with wonderful views of Mount Shasta.  3,200' elevation.  Shallow water.  Only one shallow, undeveloped public launch area at the Rat Farm.  Terrific golf course at Fall River Mills. 

I've yet to see another sailboat after 15 years of visiting the Fall River.  Anyone else familiar with Big Lake?

 

Rich Cottrell