Ski, here's the link to a cart I made to center the PA on the wheels. viewtopic.php?f=78&t=47290
I tried the smaller version ballon tire scupper cart and hated it, the weight was still to much on the arms lifting and moving it. I bought the large wheeleez cart and it worked fine. The biggest problem was getting the kayak on that cart. I do have to tilt the kayak on it's side to do this new design and it works perfect. I've had the chance to use it a few times with no problems.
I just ordered the large wheel scupper cart from hobie and should have it in a few days for an outback in soft sand. The large wheels will make a big differance moving a kayak on soft sand.