Yes, Dave, I totally agree that the windshield size is quite challenging when trying to create nice alternative models for this set.
Please check out the models for this set by a guy called Jim DeVona on Brickshelf: http://www.brickshelf.com/cgi-bin/gallery.cgi?m=anoved
His creations are truly great!
I agree with Nathanael. Good job on this model. One of the challenges that I have found with this set is that if I want to use the included windshield, I am stuck with a six-wide configuration and that can be limiting and a bit frustrating...however, if you are careful you can end up with a pleasing design.