OK got some further work done on this, here and there when I get an hour or so to fiddle. I think I'm getting closer to something I like but there's still some things I'm not quite sure of. I'm trying to pull some ideas in from Kevin Flynn's bike, specifically the rear bits. Any ideas how I might do a better job or C&C of what I've currently got? Note I'm not trying to copy it precisely, just get ideas from it.

Here's the current state:










Here's the stuff from the movie that I'd like to take inspiration from:






So my problem is the area pointed to in red:




Another issue is the area in front: I cant get these edges to fillet, presumably because the geometry is awkward. Any ideas on how to build it a different way that would lend itself to being filleted here?