The most 'work' in schlepping water jugs is from the dinghy to your boats water tank fill nozzle.

The easiest is to use a 'transfer pump' with alligator clips or 'cigarette lighter' 12vdc connection, and simply pump from the dink to the tank. Using a VERY long discharge hose from 'the pump' pushed well down into the fill hose of the tank will greatly reduce the pump load (amps draw) .... once the water goes 'over the top' of your run of hose. If you simply empty into the open 'deck cap' it will take more 'power' to pump and the pumping rate will be minimal.
Pumping is easier on the back than back straining from a 'dancing dinghy'.