I was thinking more like B. however, rather than connect the string on the left side to that bottom corner, I think you would want it to connect higher. say, in your second drawing, the peak is point A and clockwise around are points B C and D. You have the string connected from B to D. I would suggest that instead, you measure from point A to point B, and let's say it is 40". Then the string should connect on the left side to a point E that is 40" down from point A. This way when you draw it back, it will lay the fabric fairly flat along A to B, and the rest of the fabric from E to D will taper down, like a jabot, along the B to C edge of the window. The reality is that you would need to have that A to E distance be longer than the 40" to accommodate the folds in the fabric as it stacks back. Actually I think it takes longer to explain than to sew! ;) Don't get turned off by this pic which is very country and your window deserves a much more modern look, but look at it only for the structure as it illustrates what I'm talking about. The lower you make point E, the more slack and drape you will get along the top...the closer you make it to that theoretical 40", the flatter it will lay. And remember too your top will be angled, not square like the picture so the amount of fabric that s blocking the window will be much less than in this picture.

I have had the same situation in one home, reluctant to drill into the doors but, it had to be done so I put some nice rods on them. In the last place we built I had no neighbors behind me for miles and I didnt need blinds or curtains in the public rooms so they were left alone so we could see the beautiful old oaks. If not for that I wouldnt have hesitated to install sheers again. If you need privacy and want curtains you will have to drill holes, just get some nice rods that will compliment the decor. I have installed the small orb toned rods and it looked really nice bc the door handles were the same. Your other option is to hang curtains over the door and extend to just past the door so they are mounted to the wall and pull over the doors for privacy, but thats a pain when you need to get to the door you need to pull the curtains away. Or you could frost the glass for privacy but installing rods for permanent sheers is a better option, top and bottom rods, and theres some beautiful ones out there. I think you will have to bite the bullet and drill if the magnetic rods wont work. The rods if chosen to your liking can compliment the doors and curtains or some can be covered by the curtain so they are not even visible. Heres some pics of styles of curtains on a site I saved because we may be replacing a window with a french door in a bedroom. Here is a link that might be useful: french door styles and curtains

Good fabric, good interlining and lining and one has a curtain that will last more than 30 years and still look good. Obviously, if one is of the "I like change and often" school of decorating, it would be madness to spend a lot on curtains. I've always been an "investment decorating" kind of gal. If I love a fabric, I will love it for decades. I don't change things just for the sake of change - why would I if I love what I did in the first place? The DR curtains I replaced (and still loved!) were made in 1985. They lasted until 2016. The cream background had yellowed on the valances and I couldn't just remove them due to festoon blinds underneath and valance boards, whose removal would have destroyed the wallpaper, long discontinued. Didn't want to get into that! But oh, I loved those curtains - pretties ones I've ever had. I would used the same fabric again but it's now printed in the Far East, not in the UK, and it just doesn't look the same. Plus the trim has become prohibitively expensive. I went with another Colefax and Fowler fabric and the only trim is a fabric trim on the bottom of the valance, which is also simpler. They're lovely but they don't make my heart sing the way the old ones did - they were once-in-a-lifetime curtains. Grapefruit, I would agree that very few people today are willing to spring for lovely custom curtains - even wealthy people. They're a huge investment and most people today prefer change or what they see on TV, regardless of their wealth. But curtains can make a room, and if the headings are done properly, they can move from one house to another. It's really all about whether one is looking for trendy or timeless.

This seems to be a situation where curtains are not needed or even possible....i would look at alternative ways to make the wall more interesting...perhaps paint it a pretty color...add some art where there is space......or make the view prettier...if that is a fence in the back ...paint it a pretty color and even add some greenery and flower pots for annuals?..