Sounds like a very Germanic solution !
What is wrong with just swapping the pump over from one aqua roll to the other when the 1st runs out. Presumably, even with a linked system like the Germans, there will be a need to refill whichever aqua roll runs out 1st. And if the two are linked together such that water is drawn equally from both, then when they run out it will mean two trips to the tap.
Also, given the weight of a full aqua-roll (Over 40Kg) I wouldn't want to be lifting it up onto a frame. In a working environment that would be classed as a two man lift!!
And what about the waste? Unless you are drinking lots of the water, or have a waste drain on the pitch, one aqua-roll = +/- one waste master. So does that mean you also need a way of linking the wastemasters?
It all seems unnecessarily complicated to me. Or am I missing the point?