The only solution to the problem is to use shorter oars. This is a compromise because with shorter oars the dinghy doesn't row as well. But considering that 'Scouts' main propulsion is under sail I am happy to make the compromise. I took a pair of five foot six inch long oars and cut off slightly less than two inches off their lengths (from the hand grip end) to obtain a snug fit inside under the seats.
The oars are held under the seats and against the hull using short pieces of cord and jamb cleats. They are firmly in place and won't move or rattle around when sailing.