I had the same window for my masterbedroom.
Initially i wanted to put a backout curtain with linings but the problem is there's a bedside table right below the window. If I use curtain, it can't reach the ground.
So finally I decided to use blackout roman blinds. One thing bad about roman blind is that you can't cover entirely especially the sides and because I was using blackout so the sunlight coming through the sides are very bright.
Not exactly a solution to you but just thought of sharing.

if you buy the bend track, then you can use 1-piece but if you use 2 tracks then you'll need 2-piece