I wont be able to guide you properly, but if you live at home where there is Natural Gas, considered using Gas instead of petrol?
And for the jerry cans- Take a trip to Hyperstar or Metro, might find something useful there:)
I got a Angel 6200 watt generator, and i run it for 10-18 hours a day, at night for 8 hours is a must, and the rest is when i am gaming:)
It starts on gas from cold engine within 1-2 seconds, and it consumes 1.125 Unit per hour so it is quite efficient:)
Load: 1.5 Ton Split A/C, and Laptop, Speakers and 32" led.