Find a museum with a "tapestry" or quilt collection and inquire for what they recommend. In the past, the most common way that I've seen for doing this outside of framing under glass is to "tack" a backing of cotton or non-acidic fibers to the back and then hang from that. This is how the "Star Spangled Banner" is preserved and hung. Of course, over time, the quilt will be subject to deterioration due to exposure (dust, air, light). And, of course, this does slightly break the "no holes" rule because you actually have to stitch the backing to the back of the quilt.