OK. The ailerons will be better to use to help keep the wing level.
What you could do is fashion a skid for each wing tip out of small diameter music wire or old control rod. Bend it in a ""S" shape, bend one side of the "S" up at a 90 degree angle and attach them in.onto the wings on the bottom side toward the tips before they turn upward. They will ride on the ground as you taxi and keep the wing from digging into the ground.
Or buy these and install>
http://www3.towerhobbies.com/cgi-bin...?&I=LXTDS6