Jethro,
Have you seen the rear wheel strake(s) that Darin tried on his boattail? I'll bet that something similar would help you, too. The taper is quite good in most of this tail, but it looks a bit too steep just behind the rear wheel skirts.
http://ecomodder.com/forum/showthrea...tml#post149087
Also, in the last photo, it looks like the last 10-12" on the very back could be shaved down about 1/2" to 3/4" or so?