Winterize a KAD 300 with DPG drive

[Navy Diams]

Hi, I have tried to find some good advise online as to how to do the winterizing on a KAD 300 correct. I guess flushing is easy... just take off the hose prior to the impeller and add on a new hose going into a bucket that I keep full of water. Then start the engine. After 5-10 minutes I stop the engine and all the salt is out.... However now people tell me that I just make a 50/50 antifreeze in the bucket, start the engine again and stop when the antifreeze starts to come out of the drive exhaust.... Meanwhile I guess my 50/50 antifreeze will be mixed up completely with all the water in the hoses, in the heat exchanger and in the oil cooler that when it comes out it is for sure not a 50/50 antifreeze mixture anymore..... Should the system be drained at first ? (do not like that as it means I have salt leaking into my engine bay) or how much antifreeze 50/50 should I let through to make sure that I have a 50/50 antifreeze in my system ? Thanks for the help.