I've used a so called puzzle grill, over my firebox for some time and it's a great combination, but not cheap. A much cheaper alternative is available from Heine Gericke. The grill has fold out legs, and the fire bowl is a little like a metal foldable colander, but the combo is very cheap. Don't have the catalogue to hand for the exact price.
My set up will heat 2 pans at the same time. Have a look at the blog. The photos of Elvie and I cooking in the Voges show how it works.