I feel your pain man. Unless you have big equipment sand is the pits. With our small tractors it takes some finesse to move it where you want it to go. Like others have suggested lengthen your top link so your sides are raised up some in the front. That way the box blade is dragging more on the rear blade than cutting with the front. Second thing is BE MOVING when you lower the box blade down into to the sand. It is so much easier to judge how deep your cutting in sand when you lower the box while moving. Take a small cut as it does not take long to fill the box with sand. Front weight will help. Damp sand is best but wet sand is too heavy and makes it worse. In the pics You will see I added weight to my box, but in the sand cutting is not the problem it is with hard dirt and I think it is more of a hindrance. One more thing, don't go too slow as you will drag to a stop.