Easy answer for me.
Try to find (or talk Jon) into building a set of the Ohm Walsh SSC4900's.
Very light due to the tubes, HUGE full range sound.
Or find some old sound cylinders and send them in for an upgrade.
Crazy full rage sound if set-up properly and sub 50lbs easy. Not perfect, but far and away the most "full" range speaker given the weight I've ever heard.