I guess it depends on your definition of effective but I have a hard time hunting without one these days. Not having your ears blown out by a big break is really nice! Also for situations like calling coyotes cans definitely give you more opportunities at additional dogs.
The no hunting rule has to do with preventing people from hunting hogs that "got loose". Since the only hogs in MT are in the Ag community it makes sense to have them be the regulatory agency in charge. If we were to have an infestation from Canada and it couldn't be controlled the Legislature...
Making your own turrets works great! Just use the environmentals where you will be shooting and put some clear tape over it to make it weather resistant. I mark every 100 with a small hash for 50, also mark the wind hold every couple hundred for a 10mph.
The major benefit using a suppressor for hunting is that you don't blow your ears out every time you shoot. They are super effective when hunting. For coyotes especially they can't be beat and we get multiple shot opportunities that we most likely wouldn't get if we weren't shooting suppressed...