I dont think that anyone has the answer for you !!! However, making a sharp angle from the mast to the gunnel and then overboard probably wont work as lightening seems to prefer to take a straight path. It would probably be more prudent to attach the wire from your backstay and drag it in the water -- but I dont think anyone has an absolute answer because as you state this may enhance a strike. The last ''hit'' I took came down the mast/antenna wire jumped through wire in the bilge and blew into the encapsulated keel with a ''starburst'' out the side (small leakage). Perhaps a better place to ask this question would be in a general aviation (airplane) message board, and ask those who fly ''plastic'' airplanes as they seem to get ''hit'' more often than boaters. I myself have posed the queston to marine insurance underwriters.... and always get NO answer (for obvious reasons).
As a long time sailor (with 3 hits) I''d like to know what others think or have experienced with lightening protection. My ''hits'' were all when anchored or moored.
I think my preference at this time would be to bond the shrouds to external chainplates hence directly bonded underwater to a keel shoe (on an encapsulated keel) --- but I''m only guessing.