I bought an 'adjustable' curved shower rod, online. It's composed of 2 curved pieces, one slides inside the other. It's terrible - the diameters of the 2 pipes/rods are very different. There is enough room for the rod to move, and the rings don't slide over the junction. I'm guessing you can buy a solid piece, and cut it to fit. I doubt 43" will be a problem. Look for some curved shower rods online, and then research the manufacturers. Most will have details about installation, more than retailers' sites. Pick up the phone and call the manufacturer if you still have probs.

I bought a bunch from Sierra Trading post-- wait for one of their 35% or 45% sales. I don't know what size I bought and they are still packed .. but the stock changes regularly. I'd just check them out and check back. I am pretty sure I paid less than $5/set on one of their discount sales.

I got the YNL shower curtain rod recommended above from Amazon (thank you @Sarah Pecor!) and found these shower curtain hooks in brass that match pretty well from Parachute. They have a nice weight to them and when I walk in the room to me it all matches. They don’t stand out and don’t look super yellow which is what I’ve been trying to avoid. I find that brass looks different in different lighting and also different in person vs in pictures. To me it’s close enough and I’m happy with the closeness to my delta trinsic champagne brass hardware. I held up a towel rod for a color comparison. https://www.parachutehome.com/products/shower-curtain-hooks?options=color_brass

Actually had two shower curtains on my alcove shower. One was a fixed shower curtain that was hung on an exterior rod from wall to wall. It had a valance and two fixed panels, one on either side. Then, I had another shower curtain. This was a plain white cloth curtain that was on the rod. It was on rings that also included a plastic curtain for water protection. So....two rods. An exterior one. That was covering my end walls/tiles. Then, a regular bath rod that held both a fabric outer curtain and a plastic one. We no longer have this system or I would post a photo. But, yes...it can be done!