Spoilers is actuallly an option and would work well. Perhaps as well as the split flaps in front of the strip ailerons. Spoilers do generate a strong nose down pitching action when near the high point. I understand this is reduced if they are located back closer to the trailing edge. I don't know if they produce the same lift killing action at that point though. Spoilers on gliders located at the spar not only kill the lift in that area but they affect the wing to either side for quite a ways. Perhaps as much again as the width of the spoiler. Moving it to the rear would reduce that effect I suspect.