Depending on how much extra space you need, and what your desired budget range is, here's another option using two Viewpoint Spacebars side by side. Two of these give you about the same extra working space as one of the Nitto Lamp Holders, but cost less than half the price (but I don't think the Viewpoint bars look nearly as nice as the Nitto products, though). The Viewpoint Spacebars tend to run about $10 each (Performance Bicycle), but I've seen them listed for up to $15 each.