If you shut off the valve under the sink and leave the valve open under the oven, then open the drain valve under the kitchen slide it will drain all the water in the fridge water line.
Then hold the water dispenser open to hopefully let air in and let the water drain out of the fridge.
You can buy a filter with no filter in it to replace the real filter so the water in the filter is out of the draining equation.
Also make the ice maker make ice so the solenoid will open and drain water out.
If you are still worried, you could blow air through the fridge to be extra sure.
I don't think putting antifreeze into the fridge is such a good idea. It won't come out all that easily and you'll taste it.
The ice maker is one of the best things about that fridge. Get it making ice!!
Don't forget to dump it when you are done camping though, if you forget and lose power it will be a mess.
I hated the taste of the camp water where we frequent. After it goes through the whole house filter and then the fridge filter, it taste like spring water!