I am trying to use the technique known as Chiaroscuro (Ke-ära-skooro) the rendering of forms through a balanced contrast between light and dark areas. This technique was introduced during the Renaissance, the object of the effect is to try to creat an illusion of depth and space around the principal figures in a composition.
Rembrandt and Caravaggio are probably the best known painters said to have explored the possibilities of chiaroscuro and what they have in common is light coming out of dark. I'm wondering if a darker background here would achieve the depth and space you're after. Just a thought. Cheers, Malmalsmith.com