Holy cow! That is just awesome. There are so many incredible works of art on here lately!! :D
I hand quilted birds in the sky of a wall hanging once--maybe you could quilt around something? I think I'd go with the clear thead. I used that in a few I hand quilted.
I think if you take it to a superb quilter, he/she will know exactly what to do. My quilter always "sees" what would be best. When she says the quilting should not distract from the design--she meanders or stipples. But your work is such a unique design....