Get the heavy machinery to work and build up some defensive postions about 300 yards from the river. Wire the bridge to blow. Get the boats to your side. Send a couple of planes with instructions to fly high and just observe troops movements. Send about 50 people with high-powered rifles with instructions to snipe and harass, but not engage directly. Build the defensive perimeter so that 1) it is hard to see from the bridge and 2) shaped in a U around the end of the bridge. If there is any dynamite left, set a few charges on the other side of the bridge, one stick of TNT in a 5-gallon bucket filled with nails camoed it some bushes. Let about 500 of the enemy across, or until they have their RPG's on the bridge, and blow it. Have a Turkey shoot with those that got across, blow the charges across the river, and wait for the cavalry.
"Praise the Lord, and pass the ammuntion..."