I'd suggest going to visitmt.com and also rvparkreviews.com. They give a pretty good clue on what's available. Also, PassportAmerica.com has half a dozen campgrounds across the state. Obviously, there are a lot of choices near Glacier National Park. Also, lot of national forest campgrounds in western Montana. If you need some suggestions in western MT, send me a PM with some idea of the type of camping you prefer and activities you enjoy. Western MT and the Panhandle of ID have lots of choices. Have fun planning.