FEHoppy is right. Several classes of free flight competition models routinely use lifting section tails and have their centre of gravity around 75% chord, or in the case of the F1D class microfilm model below somewhere between the front and rear surfaces.
When the wing loading is very low, the induced drag from a lifting tail is minimal too. The QinetiQ Zephyr solar powered UAV used this to good effect as well. It should be borne that this and most models that use a lifting tail are virtually single speed aircraft.
Tandem wing aircraft such as the Henri Mignet's Flying Flea also generate lift from both surfaces, and if you know anything about that, you will know it can cause problems, as the forward wing at low angles of attack will act as a slot for the rear wing.
Last edited by Mechta; 10th May 2012 at 19:54.
Reason: Added picture