Yes, I know Jane will tell you it doesn't work but it does.
We bought a second-hand surfer board and attached it to the Powertrack 360 today and dd2 aged four has had a great time on it.
It's so easy to push and steer.
But in order to fix it on you do have to remove the black plastic pump holders from the rear axle. This is very easy to do and DH managed to cut both away from the rivets with a small hacksaw in about a minute. It's important to leave the rivets in place as this anchors the surfer board. Also you have to remove the hood as it restricts the space for the toddler's head, but that can be taken out of its bracket and tucked into the seat unit. Or removed completely.
So it does work!