The owner's manual for my 2000 concurs with the Class I / 2000 lb and Class III / 5000 lb limits. It also states that with a Class III hitch, the tongue weight must be at least 10% of the gross trailer weight but no more than 15%, and that an equalizing hitch is required for tongue weights above 350 pounds. Thus, you can tow a 3500 lb trailer without an equalizer hitch if you keep your tongue weight to the minimum of 15% or 350 lb. That said, I just towed a 3500 lb trailer with a tongue weight of just under 400 pounds for 3000 miles without any problems. (I bought a tongue weight scale from Sheerline.) If I were to do it again, I would beef up the rear suspension a bit, but I don't know that I would get the equalizer hitch unless I were going even heavier.
Ken