Normally, the Argosy's with the spring suspension have a 4,000# towing capacity. The hitch weight should not be an issue for a dinghy ("toad").
Some Argosy units and the later Airstream motorhomes with air bag suspensions typically had a 2,000# tow rating.
With a 5,500# dinghy, you will need a braking system for the dinghy.
My Argosy did not have any wiring for the trailer lights so I had the wiring run from the front of the chassis. I only have a 4-pin connection since my dinghy is a 1974 VW Beetle. I just use the magnetic light set.
The tow rating for your coach should be listed in the Owner's Manual.