I'm a pretty big guy (300 lbs) and I'm possibly going to take a friend for a short ride tomorrow (~180 lbs). The combined weight of the 2 passengers and the bike itself (550 lbs ??)exceeds the GVWR indicated in the Owner's Manual (938 lbs). The manual mentions something about potential stability problems. However, my primary concern is any potential structural/frame damage. Is this a ligetimate concern?