I love the quilt! If this were mine, I would add 2 narrow borders in green and a gold, then finish with a larger border in the browns you used in the quilt and do prarie points that would mimick the flying geese . That would give you the drop needed for your bed..
What ever you do decide, I am sure it will be wonderful. You could also repeat some of the pattern from the quilt top along the sides.
Good luck. I hope to see it when it is complete.