I've never seen a bunk arranged like I did for our kids, an elementary boy and girl having to share a 10'X12' room for 3 years. We put the bunk in the middle, ran a sheet of pegboard on the left side of lower mattress to the bunk above, and a sheet of pegboard on the right side of the upper mattress to the ceiling. Voila - "2 rooms" in one. Our daughter wanted the lower right side of the room for her dolls, dresser, and books. Our son claimed the upper bunk and the left side of the room for his planes and Legos. They shared the 4'X12' entry and the closet but had separate spaces to play with friends. Wish I had taken photos!
That sounds very creative and a great use of a small space!
I wish you would have taken pictures too. I'm have same situation with my kids and am trying to figure out a way for them to have there own space.