I know its been said that guests cant be made to get off once the cars enter the station however how about having a duel loading station. the station would still have the one queue however would have parallel tracks that can both load and unload as normal though when a car enters the station it simply picks the side that is currently empty. this would reduce the queue times for the coaster as i have always found that the bottle neck is in the station as we have to wait for everyone to completely exit before the boarding even begins and having duel loading would solve this problem.