Re: tow rig
What does the owner's manual say about towing capacity? Let that be your judge, and try to stay at least 25% under the maximum. Also, yours is 21 years old, now. What kind of condition is it in?
Towing is hard on transmissions, engines, and cooling systems. How are those systems on yours.
Scale down your boat size if everything's not in good condition.
Also, remember that you'll probably be replacing this vehicle eventually. The boat you buy should be part of your decision on what to buy next.