bi wing zagi
I don't own a Zagi but every other guy at my club does. I love those figure eights with the wingtips dragging the runway. Keeeoool.
By all means, try your idea. I would connect the two wings with structural tip plates and some type of vertical fin in the center. Coroplast would probably work. Velcro and tape seems to be the fasteners of choice for the Zagi crowd.
One cool thing you could do is add rudders on the tip plates. Then you could do stall turns. Extra Keeeoool.