if your thinking of doing that in the hope you wont have to buy a new boss then dont do it. the shoulder is there to limit your top speed by stopping the variator from extending fully., if you put it in backwards then you will cause problems with the variator because it wont sit properly and the belt will sit at an angle and might cause it to twist and possibly break. just buy a smooth boss, dont put it in backwards.
hope this helped
safe riding