I checked and D200 fires inside MDX-200 housing. One just needs to remove a little plate (routing wires for regular sync cord).
Then there is just enough space to make it work.
Are such bulkheads housing specific or is it some standard?
i.e. can I use Hugyfot for S&S housing?
I have a DX-D80 (for Nikon D80) camera and have tried something similar with a the Hugyfot acrylic optical plug.
My experience below is from the DX housing, I'm not to sure if the bulkheads will be exactly the same as the MDX housing. Your mileage may vary.
The electronics of the bulk head were easily removed by desoldering the wires to the bottom of the bulk head and removing a single C-clip. The electronics in the bulk head could then be removed and the bulk head was empty. The Hugyfot adapter then screws into the empty bulk head with the bottom of it protruding just below the end of the bulk head. However, there is one problem. At the bottom of the normal bulkhead there is a little metal notch that prevents the strobe connection from rotating when it is inserted. This notch causes the bottom most o-ring of the adapter to not sit properly and it is pushed up, making it very tight to screw in the adapter. As this o-ring is providing the waterproof seal, I am worried that it might become kinked and let water in. I've tried the housing in the pool and it doesn't leak, but have managed to take it any deeper on a proper dive yet.
There would be 2 options to fix this:
1) Grind away the small notch at the bottom of the bulk head. Given the limited space in the bulk head this would be quite hard.
2) Cut a groove in the Hugyfot adapter that is a bit higher up for the o-ring to sit. I'm not sure if the plastic would melt on a lathe, if you wanted a nice clean cut.
Lastly, if your D200 will fire the flash inside the housing you don't need to modify it at all. To get my D80 to fire, I did have to modify it as the flash didn't quite have enough room to open up.