Teardrops n Tiny Travel Trailers

I WAS INSTALLING AN OLD WORKS BOX WITH THE EARS THAT CATCH TOE BACK OF THE DRYWALL BUT THE LITTLE ARMS HAVE TO BE ABLE TO SWING??? HOW AM O GONNA SWING AN ARC TO CLEAR THE FOAM WITHOUT REMOVING THE DRYWALL??? THEN IT HIT ME AN ALLEN WRENCH MADE A NEED LITTLES ARC IN THE FOAM