That’s the video I ended up resorting to for the main coolant system since I couldn’t get to the lower drain.
I detached the same hose, had 2 gallons of distilled water near by and would get in the car and rev it for a few minutes (3-5 I found) and then go top the system off. It definitely took some time and would have been faster with 2 people but it was my only option and all I have is time.