We were originally going to use a one ton chassis Dodge van with a camper converstion. According to the mfg, the tow rating was about 8K pounds. From discussion with other CD-25 owners, we figured we'd be over that weight, and decided to get a diesel pick-up (15,000 pound tow rating). When we weighed our boat, equipped for cruising, less than 1/4 tank of fuel, full water (dingy and motor were in the truck), it weighed about 8,400 pounds on the trailer.
No experience with the C-Dory, but we did have a Grand Cherokee Limited (360 ci) that we used to tow a sailboat that was around 4,500 pounds on the trailer, and it was marginal. I don't know about the Commander, but the Grand is built with unibody construction... IMHO good for the ride, but not as good for towing.
HTH