Ron,

My 360 has no particular holes in the control surfaces aside from the
cavity connectivity. They don't get water in them.  However, a major
danger in my tail area existed for a while.

The elevator while held by control lock in the up position encouraged
water to flow along the horizontal tail skin into the tail of the
aircraft.  The tail tie down hole was not sufficient to allow this water
to escape.  One bay aft of the tail tie down I'm sure I was getting 2-3"
of standing water.  Both aft CG issues and overnight freeze (ice
expanding destruction) were concerns that drove me to add a drain to my
tail.

Larry