Just picked up my 17foot glide, i had a fin box put in as i felt i didn't use the rudder enough, and that it would go better in flatwater as i could stand further forward, they made me a custom 12inch keel fin, haven't tried it out yet but it looks the goods so hopefully it will go just as well
Jarryd
Cool, let us all know how it goes. I had my fin box put in slightly back of where yours is and I tend to prefer a low aspect/large area fin it (but that's just me, YMMV ) .
they put it in just behind where the stock fin was pretty much right under the back tailpad, so it is right where my back foot goes when im catching small waves or in decent downwind conditions
Jarryd