Im guessing this isnt finished yet so heres a suggestion on fixing those wheel arches, what you can do is build on top of them making new wheel arches that are only a fraction bigger that will attack to the current ones with the new ones obviously being rounded, you would need to redo any extras you did on the wheel arches including painting them but it could work, also for the bundle of canvas or what ever it is on the backseats it looks like it needs a second strap in the second indentation, it just doesnt look right.
Apart from those things it is amazing, and I look foward to seeing it finished