Maverick,
Hi and thanks for the ideas. It does seem if my understanding is correct that you will be relying on the strength of the glue joint between the ali and the skin. I think I might have a go in a similar manner but create a slot in the bottom of the fin allowing me to feed the shaped hardwood or ali up into the front of the fin. Then you have a sandwich of the fin skin being pulled down onto the fuselage. It is then possible to reseal the entry slot with some carbon plate which also might be a contender where one has used the ali.
There is an elegant solution to this so we keep listening so to speak.

Regards

David