I'm not sure why you are going to such mechanical means of allowing the rudder to flip up, the Stealths have been sold in sufficient numbers to flag up whether the cassette rudder used is a problem and likely to get broken. All the Stealth owners I know seem to have had some stage or rather a dagger board broken or damaged by hitting something which seems to indicate that its not the rudder that takes the impact but the dagger board.

If you want to make the T foil adjustable then I would suggest that you take a look at an older fibreglass glider which has an all flying tailplane, the principals are the same and open to inspection. Its interesting that the all flying tailplane was quickly dropped due to quite a number of problems at higher speeds ( uncontrollable flutter ), they are all now like a conventional wing with only the very last part of the wing adjustable.

In the surf I know many Stealth owners simply put a small elastic section around the back of the rudder locking it into the cassette, any bangs from below simply drive the rudder upwards out of the way and is retained there by the elastics friction, rather crude but seems to be effective.