What modifications would be required to use a DHC-6-400 for Carrier Onboard Delivery work? In the spirit of our small airplane landing on a carrier question, I decided to up the ante slightly in a couple of ways.

Let us say some enterprising foreign navy has found a small flattop under their Christmas tree this year, and is in need of some aircraft to fly off it.  Of course, tactical aircraft are a necessity, and to that end, they could obtain some used A-4s as a starting point for their fledgling naval aviation branch.  However, there are other important aircraft on a carrier deck, one of them being the Carrier Onboard Delivery plane.  A bright young naval officer there decides "Hey, we should see if some small civil planes might work for what we need", and does a bit of research, stumbling upon the DHC-6-400 with its widespread support base, ease of maintenance, good STOL performance, and current production availability.

How much modification would our enterprising foreign navy need to ask Viking Air to do to their order of DHC-6-400s to be fully usable from a carrier deck?
DHC-6 has a reported takeoff roll of 210m and landing distance of 155m and as such can be operated from most of the aircraft carriers in service, albeit with limited capability. If required, the aircraft can takeoff into the wind and for arrested recovery rear fuselage can be strengthened, though this looks unnecessary.

It may need some changes for operating in marine environment like,


better corrosion protection
strengthened landing gear
Required naval equipment (for TO/landing).


Of course, all these modifications will eat into the payload. DHC-6 would be a rather small COD aircraft. The C-2 Greyhound used in USN has a payload greater than the MTOW of the twin otter.