A quick, cheap, easy, way to secure the sandbags. Take a used 2x4 or 2x6 and cut it to the width of the inside of the box. Place it on the bed behind the wheel wells and put the sandbags between the wheel wells and tailgate. The 2x will keep the bags from sliding forward. Leave the 2x there during the non-winter months to keep other things from sliding forward. You can make the 2x look better by buying a new 8 footer and giving it 2 coats of a semitransparent preservative stain (or any other wood preservative you or a friend or neighbor have on hand).
Bright Red 2003 Edge Plus, 3.0 liter, reg. cab, 4WD, manual trans., 4.10 rear end.
Mods: Speedliner spray-on bed liner. Air box mod. K&N drop in air filter. Gibson Sweptside single pipe catback system. James Duff traction bars (above the springs type). Delta Industries black polyethelene truck box (mounted on the driver's side of the pickup box between wheel well and cab). Hidden Hitch receiver hitch. Side window visors. Door pockets.