I actually did that once for a bay window in my living room. Rather than using sash rods, I used dowels and tubing. It worked OK! I have since decide that I like the treatment on the outside front of the window, so abandoned the homemade rod, but it DID work!

HI, I know i am late commenting on this one, but we are spreading the word about a new bay curtain pole that doesn't have brackets at the corner so you can have eyelet curtains which i think would be perfect for what you are looking for. The pole can hold utp 30kg and is amazing. Your eyelet curtain poles can go around the corners without being obstructed by brackets, this means that you can have a pair of curtains working around the window and then drawing back out of the way. This pole is only suitable for 3 sided bay window. Eyelet Bay Curtain Pole You can purchase the eyelet bay curtain pole below. Please see the video below and the image

It’s for a rental. Perhaps you are overthinking it? Generally you need to focus on tenant-proofing. Is this Airbnb or extremely upscale? Furnished?

Here is a mock up of what you have considered. I think you could opt for 2 rods also if you prefer.