I think the branch is fine. In one of my tanks with an upstairs I use a stick that I put on a slant like a ramp and then push the lay box against it to anchor it. In the other tanks I use either the lay box or a hide that they can climb on top of.
I use that white stuff that you croshay (sp) with. That that stuff that si sqaure. I did the same idea. Exept my legs are square and my dad built it. They love the second floor!