One solution is to try to mount the drive sprocket inwards.
Remove the mounting pin.
Drill a new hole through both sides of the hull, slightly inward from where the original mounting pin was. Use the tracks to determine the location of the new hole.
Get a piece of styrene rod that is the proper diameter and cut it to the proper length (width of hull plus enough to mount the drive sprockets on to). This piece will become the axle.
Mount the sprockets onto the new axle.
Styrene rods can be purchased (Evergreen) or a straight piece of sprue can be used.