I found a better picture to reference. This is my set-up with stock fenders on it. I don't have the rear fenders any more.
I measured the backspacing of my wheel. It is indeed 3.5" from the rear lip to the mounting surface. It is 5" from the mounting surface to the front lip. I'm assuming therefore, my sizing is 8" 3.5"backspacing, or 8" ET -25.
On another note, I wish I could get some camber on my front wheels...