I have not seen a conversion done, but think it might result in a nice ski. I would think it would be strong enough for most paddling, but then again, I'm not the one to say, as I have difficulties putting two pieces of Lego together . . . You might not get a sense of how strong the mod is until after it's complete.
Swap out the stock rudder for something a bit more effective - that early Fenn rudder was really "drag-y" while turning the ski.
Please post some pics and a report if you get the conversion done.
ERik Borgnes