James, from a training standpoint, you're better off with something like a parachute bag. http://www.armysurplusworld.com/prod...roductID=17939YOU MUST ENSURE YOU ANNOTATE ALL LINKS WHETHER WORK AND FAMILY SAFE.
It's side loaded, which is ideal for sandbag work. We put 200 pounds in ours last night, and I had a dude ripping it off the floor for sets of 5. I have an A bag also. If you're just wanting to drag the thing like the dummy in the test, use it, but you'll need to stuff it with a quilt or towels, as 150# of sand, (pea gravel is a much better option), will not take up that much room. Those bags are huge! If you want something more versatile, go with the parachute bag.
Another option is drag a tire loaded with 100# (pea gravel ducked taped up). Use a shorter rope so that you mimic the posture you'll need in dragging the dummy. Or use backward heavy farmers carries while dragging a tire tied around your waist. (I've had 3 guys come in with the highest scores on the recruit fire fitness test here).
Just my thoughts.