kfp673, you shouldn't have to remove your tailgate. I'm new to towing a 5er, but so far the tailgate has not been an issue. I've seen both short and long bed trucks towing with the stock tailgate. The aftermarket tailgate seems to be easier but I don't plan to get one. I just let it up and down as needed. As for the incline, haven't had that issue in the time I've had mine. Be interesting what others who have towed them for a while have to say.
Fred & Teresa
2005 Coachmen Encore Sportscoach
2005 Harley Road King
2002 EZGO Golf Cart