Ravenwing Killhawk

So I got it into my head that a flying transport for Bikes would be pretty cool, and to take advantage of the Stormraven and give me a new hobby project, I have begun work on the Ravening Killhawk. The WIP rules for it can be found here. To make this I am using the parts from the Stormraven and Valkyrie.

I'm liking how it is coming out, but I am having real trouble figuring out how to make the tail fins work out. Plasticard is on option but I hate plasticard. Foam is also likely.