Not sure I would use the Roxul unless you just don’t have other options. NoRez is really good, easy to install and really helps damp lively box walls. I also like cotton acoustic insulation, natural wool and even felt for mid range and mid woofer boxes. Good old fashion fiberglass insulation is surprisingly good for bass.
If you are stuffing boxes to increase the volume the woofer sees for tuning, some trial and error is par for the course. I prefer a correct box tuning than lots of stuffing. Hard to cheat the laws of physics and you can easily “over stuff’ a woofer bin and mess up the sound.