Thanks to persistance, input from another Brat (Sweat Pea), patient sales staff, and a good return policy at REI, I was able to find the pieces from Thule to put a nice "factory" rack on our 25 cruiser. It attaches with clips to the roof mounted hand rails and big rubber feet sit near the edge of the roof and support the actual load weight. This rack is rated to hold about 200 lbs and I have used them to carry up to 3 18ft kayaks at 70+ mph for literally thousands of miles on cars over the years. They are sturdy and under rated. I know folks who have hauled over 400lbs without incident on these types of racks. It may fit other models of C-Dory but I cannot promise that.
Yakima also has similar components that can work but they use round bars for cross bars typically and that allows for an annoying rotation of your kayak saddles or other rack components when you need them to stay put.
Here is what you need to purchase:
1 set (4) of 400XTR feet and 53 (inch) Rapid bars or longer.
(they make a 47 that might work but would be pushing it)
or
1 set (4) 400XT feet with 50 (inch) Square bars or longer (I used these with a 58 inch bar)
1 Clip Kit #191 which is made for a 1992 Izuzu Trooper but near perfectly meets the dimensional needs for a roof/rail mount on a CD 25. This piece was the tough one to find becuase the clips are all made for cars so you have to cut open boxes and examine them for yourself. IT comes with bar caps for the square bars so don't buy a separate package of them.
I found that 8 1/2 inch rear and 8 1/4 inch front bar overhangs were about right to position the feet on the roof and have the clips grab the rails well using 58in square bars. This was measured on the top of the bar from end to outside edge of the foot bracket.
Add 4 lock cores if you want to lock it on the roof and then just add the bike, boat, cargo, ski? attachments that meet your needs.
$160-165 for the feet
$70 for the fit kit
$70+ for bars
$55 for locks
add rack attachments.............not cheap but very sturdy, flexible, lockable, and removeable with no hole drilling required.