What are the thoughts on putting antifreeze thru the lines, then draining or using the pump to remove most of the antifreeze? There wouldn't be any water left in the lines, only a small amount of ant...
I don't see any problem with it since the antifreeze will displace all the water. However, I question any time savings you would actually gain because you still need to flush out the system. In any case, what you are proposing seems fine to me. Good luck.