Rutan's Quickie is actually a tandem wing setup and not really a true canard. Could you tell us if it is a scratch build or a kit? When you say it is wobbley do you mean just left to right (yaw axis) or do get it up, down, roll left and right too? Also since your title to your post mentions glide, is the problem happening only when the power is off?

The constant chord in the wing is not the problem I suspect. More likely would be the center of gravity would be my first guess. Where does it balance in relation to the wings?