2 Litre Metal Can (Petrol) (Northgate Village CH1)

Hi : O ) I'm going on tour on my C90 and looking to extend my mileage with a 'reserve petrol tin'. I would like it to be metal and rectangular to 'seat' securely on my luggage rack. An old 2L Paint thinners can or similar would be ideal, but it must have a aperture big enough for the petrol pump nozzle : O ) Thanks for looking Cheers : O )