I don't know why it wouldn't work. I handquilt without a hoop or frame; I drape it over my ironing board and "puddle" it on my lap. I've done 2 queen-sized this way and they turned out fine. It's all a matter of keeping the tension on the quilt even. I think you'll do fine. Try a small section and see how it goes; it's easier to remove handquilting than machine quilting.
Good luck--it's a beautiful quilt.