I'm admittedly a google coach, so take this for what it's worth. I found this article on a 3-5-3 defensive set, do you think our D could be a hybrid of a 3-5-3? It's built for small players with great speed. Check out the link, it's pretty good stuff.
http://www.chiefpigskin.com/beginners-guide-to-the-3-5-3-defense/
http://www.chiefpigskin.com/beginners-guide-to-the-3-5-3-defense/