Trailering to a race in freezing temperatures

I reason I was thinking of putting some antifreeze in it is because I can’t completely drain everything easily. Draining radiator gets about half the system drained. Running the electric pump gets about half of what’s left and pulling block plugs isn’t easy to do without a lift but even that doesn’t get everything out does it?

Also, what about for the trip home? Should I drain and dispose new race coolant?