Better top-snap behaviour for ultrawide monitors

I have an ultrawide 3440x1440 monitor attached to my MacBook Pro so the snap to left/top/right behaviour available on the General tab (of BST 1.9.8) isn't ideal, as a fullscreen window (drag to top) is absolutely huge and even a half-screen window (drag to left or right) is still a bit big.

What I'd prefer is for drag-to-top to give me a full height window that's 1/3 the width of the screen, with the position being determined by whether I drag to the left, middle or right third of the screen top.

Yes, I know I can configure a right-click on the R/G/B buttons to position the window in this way (I already have) but I'd find a drag more intuitive. I could probably do it with Customer Snap Areas too, but again that's too much hassle.

A colleague has a super ultrawide monitor (3840x1440) which is basically 2 "normal" monitors wide. For this I think a drag-to-top making the windows 1/4 the screen width would be better, so maybe you could make the behaviour configurable.

Such custom drag preferences are exactly what the custom snap area feature is made for. You can easily set them up to do exactly what you described.