Cool concept, and the proportions are working pretty well, BUT, I have to agree with others in that the wheel base now looks too short, kinda like a tail-stander drag car.
I only say so because you've put a LOT of consideration in to all other aspects, and this could look SO nice with that extra bit. I will say, too, that the model appears to be sitting a bit lower in the back, and that could be exaggerating the effect somewhat. Here's a quick and dirty Photo-chop to chew on...
(Following with much interest regardless!)