Haven't read the whole thread but I'll reply.
That banner looks to me like large format inkjet.
It's usually printed on Flexface which is reinforced vinyl used for outdoor signage (especially backlit signs). I know this as I was a production manager at a sign company and we made signs just like this. Not only are large format inkjets very expensive, they need a very special computer setup with closed-loop color correction.
In you opinion could this be done in two to four hours?