I have the same kit (09 and newer though).
What I did was mount the skins temperarily to the tank and cut them how I wanted it to look.
This pic is before the cut
Then I modified the stock seat to match up.
I have since made my own fiberglass seat pan and making my own custom seat. Doing it this way, it matches up perfectly to the tank.
If you want to make your own seat pan I can post up a how-to I did for another forum. Its pretty simple to do and only takes about $30 worth of materials. Not to mention the pride of doing it yourself which you can't put a price on.
Here is the last picture I have of the seat pan I made. Leather is getting tooled right now, and padding should be here today. Im hoping to have it all completed in the next couple of weeks.
Where you at in Kansas? If you want to do a fiberglass pan but don't feel confident enough maybe we can get together and I can help you in person. Im in the SW corner, north west of Liberal southwest of Garden City.