I hope I do this right (the link) but check out Johns work at the address shown. Its that same concept, I did it on my night heron and it works great. You can always add or subtract from it.
Tim

: Another option is to make the external stem on the stern deeper than it needs
: to be so that it effectively becomes a skeg about 2 or 300 mm long but
: only about 5 or 10 mm deep. It is big enough to have some effect, but it
: doesn't actually look as if there is a skeg there.

: It is a bit like eliminating or at least reducing the rocker at the stern.

: Then when you discover that you didn't really need it, you can just plane it
: down and glass over it and no-one will ever know it used to be there.