You're very welcome, AlexC.
Before I studied architecture, I had three years of training to become a Technical Drawer; to create or read those "blueprints" is second nature to me. Which makes me confident to have shared the fastest way. Thanks for checking this out.
Your intuition about the Arc was not off.
It can be done with an Arc, four of them, but the problem here is that the center point of each Arc is not in the center of the tent. This causes a lot of trial and error, especially since the "blueprint" has no orthogonal view to this quarter arc, like when it lies on the ground to be assembled. The radius of an Arc here is 12.80m-13,50m (+/-) based on taking it from the "blueprint". Using the three orthogonal view (Multi View) re-engineering method is faster and has no guess-part in it. Anyway, your intuition was good.
Enjoy your project