How about this for an Eco camper...might take 4 days, 20 recharges and a thick jumper to get to Commerfest but it'll be quiet.
http://www.ebay.co.uk/itm/MILK-FLOAT-/251767354558?pt=Automobiles_UK&hash=item3a9e80f4be
The Blue Toaster
http://www.ebay.co.uk/itm/MILK-FLOAT-/251767354558?pt=Automobiles_UK&hash=item3a9e80f4be
The Blue Toaster