I don´t see how you can go below 8lbs. Wings, stabs, rudder and turtledeck are presheeted, and the fuselage sides are plenty lightened. Any further lightening could compromise the structure. You will not find anything lighter than the push-pull setup used for the rudder and elevators. Other than that, using a lighter engine mount, carbon landing gear, maybe smaller servos and Powerflites would give some savings. Bear in mind the plane balances perfectly with the radio equipment in the standard location (e.g. wing saddle) in my OS 91 fx powered plane. Mine is about 8lbs dry.

One thing I noticed the plane is pretty fast for a 3D machine with the APC 13x8. IMHO, the plane cries for a good 4 stroker for better speed control.....