If tillered well it will take that long of a draw with out a backing no problem. I've made 58"ntn ridged handled recurved osage bows that are drawn to 29" all the time. I've made 50"ntn recurved semi-ridged handled bows that draw to 27" all the time. That rule was more intended for beingers I think, and as your tilering gets better you can get away with much shorter bow lengths.