Simply from the aesthetic side, we can sew mount this to a complimentary substrate. (We'd have to see the silk and color to make design choices.), and a deep enough moulding to nicely accomodate the dress, but you're obviously looking at a frame design at least 60inches x width. Without even seeing the item, I would guess that you're looking at over $400 and closer to $500-700 to frame this well.
UV glass will filter out 97-98% of harmful light damage. The exposure of light and other environmental factors where you hang the completed project are the only other real UV issues you can control.
Bright sunlight hitting the framed project directly or flourescent lighting would be the most harmful.
Please email Sarah@theframeworkshop.com directly if you desire to pursue this project.