I bought my PaddleCart slightly used at a very good price. It looks like a real quality piece, but I found that it would not fit my very wide (30") Perception America; the kayak just slides over this way or that, as soon as I start to pull it along. It becomes completely lopsided and really a pain to handle. I can get the cart/boat combination to work, if the kayak is upside down, but that creates other problems, like having to carry the paddle, dry bags, etc. separately, and fumbling around to grasp the boat's carrying handle.
I think this problem can be easily and cheaply solved by a simple modification of the position of the bars that support the boat. Of course, my preferred solution is to get a slimmer, higher performance kayak that will fit better.
As another user pointed out, there is too little space between the tires' air valves and the wheel hubs to use a bicycle floor pump or my other two hand pumps. A service station air hose might fit, but it would probably explode the tires. With some wiggling, I can use my bicycle's mini-pump, but then lots of air leaks out when I struggle to disconnect it. The obvious fixes would be to have the valve stick out at a slight angle, or to use a tube with a shorter valve or a wheel with more clearance.
Now that kayaking season is almost over, I'll have time to try to figure out a way to use the PaddleCart with my tubby boat. It's just too nice a piece to get rid of without trying to make it work for me.