I think I managed to do it!!! I really think I've made it with Mr Spot's method!
I only have a question for Mr Spot: when you draw the walls that go under the side ramps, do the walls have to snap to a mid point of the ramp or do you just make it by eye?
Scott: thank you so much. You guys have been great Actually... it's kind of funny. Architects back here aren't really this helpful amongst each others... You guys already earned a spot in heaven =)