I would create it exactly as you indicated, but I would place the ribbon against the cake so it was sitting on top of the chocolate trim.
That idea might work, but I would try it on a small cake first. That cake is really beautiful.
I would put a band of brown around the bottom and then cover the top with aqua. The ribbon would then cover the join in the middle and no overlap ridge.
Thanks everyone!! I think i will practice on a couple of 4" cakes i have sitting in my freezer!