According to Four Winns: A 1998 180 weighs 2480 lbs with a 4.3 V6 engine, 2320 lbs with a 3.0 and 2100 lbs with a 130 HP outboard. The trailer weighs 800. All are under the 3500 lb mark.
That said, add fuel, food, drinks, lines, anchor etc, and the V6 will likely be over 3500, but not enough to matter much. Regardless, manufacturer tow ratings, like oil change intervals, are guidelines, not law.
see:
http://www.fourwinns.com/upload/Docu...0Sportboat.pdf