Here is what I banged together. With this set up you have a grade of 3.6%, definitely manageable. I suppose if all your engines feature the wonder of Magne-Traction then maybe you can get away with something steeper, but 3.6% is plenty.
Unfortunately I had to take out the siding, and I tried to arrange it so none of the tracks are directly beneath the others. Obviously it's all up to you how you want to tweak it.
Let me know what you think!
