I do not know what the AT-6 flight manual might say on the subject, but the roughly comparable T-28B flight manual directs gear up landings for any off runway events
Gear up or down, The T-6 manual leaves it to pilot discretion. T-28 high altitude, options given bail out, landing gear down on runway - low altitude, gear down on prepared surface, gear up on unprepared surface or into water.
Saw it happen to a T-28, ailerons jammed on the overshoot from a field carrier landing at Barin Field (close to where this T-6 accident occurred), pilot closed throttle and landed, aircraft immediately speared off the side of the runway where upon he raised the gear, as called for by the manual, little damage.