CT has a no front plate law. I don't have a front plate, never been pulled over / harassed for it.
From my experience, especially so since I am dark in color, you can do one of the 2, but not both.
So no plate + no tints or plate + tints.
To be honest with you, I had 20% tints on both my cars before the M3, and I actually LOVE not having tints. Sure I can't pick my nose anymore in traffic, but now I just use tissue paper and blow my nose.
I think if I had an SUV or an exotic sports car I would put 15% or Limo tint on it. But for my M3, I like looking around, and don't mind people looking in!
....But in your case, I'd say go front plate + tints because it seems like you really like your tints.
My M3 is for sale here