Jeremy,
I think that all 2000 Marquis coaches have the same receiver (hitch). If so the receiver will be your weak link. I know of two 2000 Marquis coaches that have had receiver failures. Both were caught before the receiver completely broke in two, but the welds were the receiver attaches to the square tube that runs between the frame rails, broke on three sides before being caught. One coach was towing a Suburban and the other one was towing a 4600 pound Grand Cherokee. The one towing the Grand Cherokee was my coach.
If your receiver is butt welded to the cross tube and only has a reinforcing plate across the top, it is a 5000 pound hitch and should be reinforced or at least watched carefully if you are towing an 8800 pound toad.
Gerald