I like your solution, but I might suggest a period or two of sudden-death (first to score wins) before resorting to corner set plays. The most exciting sporting events in North America are NHL playoff games in sudden-death overtime. One question, at what point would the corner try be deemed to have failed? What if the ball remains live and the offense maintains possession? Would play continue? What if the try results in the defense last touching before the ball goes over the end line? Would the offense get another try within the try?