the only reason really to use heavier material is for support...the bigger/heavier the woofer the more rigid/supportive the material needs to be.
(my woofer weighs a ton that's why I used 3/4)
if you're only using tens (unless using W7's or something similar) save the weight and the money and use 1/2"
if constructed and braced properly it'll be fine
double up the material around the mounting hole with a ring of wood the size of the woofer/opening on the inside of the box so you are now mounting the woofer to an inch of thickness instead of 1/2
research box building methods and you'll find a ton of info on how to do this
scene: Agaudo smashes cockroach to provoke ventura
Agaudo: Homicide!, ventura how you gonna solve that one?
Ventura: Good question Agaudo,first I'd establish a motive..in this case the killer saw the size of the bugs dick and became insanely jealous!