Me I have 2 trolleys
The first one Big Bertha carrys 8 x 25 litre barrells of water plus the battery - pump box and poles.
The second one Little Bertha which use to be one of Peter trolleys, carrys 2 x 25 litres of water plus battery - pump box and pole.
So all I do is walk down the road and clean the fronts with Big Bertha and the backs I do with Little Bertha.
Of course I only fill up with what water I need, and I always go down hills when the trolley is full and up when its getting lighter.