Basically keep the wings, tail and power on or near the center line. Keep the fin/rudder short and wide. Use a symetrical airfoil and balance the model far enough back that it's pitch neutral. No dihedral and even side area above and below the center line of the fuselage......

Sounds sort of like a pattern model doesn't it?

What do you mean by "plank wing"? If you mean a constant chord wing then there's nothing that says it won't do a decent axial roll.