Who's looking for trouble? I'm looking at a 325/30/19 Nitto Invo which is a "narrow" 325 tire...Compared to some other brands it's as wide as their 295 or 305...If you're running a 315/35/20 it's a lot taller and that's why it would be much tighter fit...
It will rub in the wheel well or wont be flush with your fenders imo. I know Invos are not as wide as others, my PSS are a few mm larger than the Invos in 315/35/20.
Look at all the svt members signature, very few run 325 in the back.
Try it and prove me wrong but i think you'll regret it.