I also would go with the 9th as primary quesited significator, with 10th as secondary quesited; however, with my extensive use of Lots in horary (mundane, event and even natal too) I would, myself, take the Lot of Successful Outcome as primary quesited significator, and see what the relationship of querent significator is to the Lot and its dispositor (lord or significator)
LOSO formula = ascendant+jupiter-sun (same day or night)