ST,
I like the sunburst idea.
The cowling is not a huge problem to mount. I would use MEK to join the halves. Then measure how far the spinner backplate is from the firewall and add a 1/16th. Then use some Dubro #2 hex head screws and use them to screw into the sides. Once located, pull them out and add some 1/16th ply and epoxy them to the center of your screw holes for some meat.
The hard part, or fun part, is to cut out the cylinder hole, and then follow with the muffler hole. Only cut out what is needed to clear the muffler and add two 1/4 inch holes on the other side so you must remove the muffler to remove the cowling, that way there is more to the plastic structure to maintain integrity.
Save the scrap so if you mess up, you can add back to it with MEK and carve anew. When finished, sand it down so it's smooth and paint it up.
Google DeHavilland Chipmunk, Skip Volk, Don Lumley, Art Scholl, etc. to get some good ideas for paint schemes.
Looks good, have fun.
Chris...