It was a FatSEAT, not a sac, the sac worked, just not as good. I think the SEAT was said to be 1100 lbs alone, but never weighed it. Just filled it up and rode. Sold it to someone else with the same boat and they ran the exact same setup.
Try one sack in the back, then maybe two, in the back on the sides of the engine, and def put some in the nose. Climb in there and get it way up front.