I had a similar townhouse years ago. Most of the neighbors put the TV under the stairs and the sofa facing the stairs. Instead, we put the sofa in front of the stairs and the TV on the wall opposite. We then had room under the stairs for a set of graduated height bookshelves for book and photo storage. And it looked more dimensional.

We also had our 'office' set up between the living room area and the dining room area on the long wall.

What do you mean, 'extend in front'? And what do you want help with? Is your drawing something that has been built or are you trying to architect your own house plan?