You could just take a cuttings and put that under light for a few hours a day then place them in a light proof area for the rest of the day and they would show sex that way. It would be a small hassle but since your limited on space you could do it that way without stressing your plants. There are some growers who "revegg" plants that have been fully flowered , so unless the strain is hermie prone it should be ok. You could use a product like reverse to counteract any stress induced hermie traits your plant might have also.