I just bought a 2010 Double Cab and the rear windows are tinted fromt he factory. I would like to tint the front 2 and go darker on the rear. I was thinking 5 % on the front(illegal I know) but I also want to match the rear to the front. I was thinking that 20 % on top of the already tinted glass would be close. Has anyone done this, or have any input about it.