Dave, yes we have had both stolen whilst on site, and also had the Aquaroll stolen , along with other stuff when in storage.
We take just about everything home each time now, which is not to clever as we use the van almost every week during the summer. On site, we use the cable bicycle locks and pass one end through the handle, the other round a corner steady or through one of the cut outs in the van chassis, and lock the ends together.