When our camper was dealer prepped the day we picked it up, the fresh water tanks were filled and flushed, along with the low point drains. So hopefully, some of the antifreeze was flushed. We will get the rest on Friday.
I also have washer-dryer prep in the front "closet' that will also have to be flushed. We will not be using it, but will flush it so as not to contaminate the rest of the water system. And yes, we do have an outside shower hookup and I will also be flushing that as well. After that, then it will be time for some fun!