You might want to set a piece of plywood on top of that thing to keep the bits of rubber from going awol when a round hits it. Cardboard stapled on top may even be enough to keep from loosing material.
Also, you may want to consider making the sand trap section removable. That way you can carry two items that are each of lesser weight. On my big trap, I built it so that the rear steel plate is easily removable for just that reason.