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450kg/1000 lbs for lead acid. Which is about $4000 worth. You'll need a truck to drive it around, but you'll be better off using the truck to haul around that same weight gasoline around and using it to run the engine which will run much much longer than 8 hours. Or just idle the engine on the pickup with its normal tank which it can do for more than 8 hours.
Use fuel, not batteries. Practically any exothermic chemical reaction is more efficient. If you need clean burning then use the CORRECT alcohol as a fuel. There are multiple types and some aren't good to burn.
To embellish the point made by dknguyen, 2kW is about the same heat as is produced by 40 1" candle flames. Consider how small and lightweight 8 hours worth of that might be, compared to almost 1000 pounds of lead-acid batteries, to say nothing of the cost!
You could use LiFePO4 batteries to reduce the weight to around 400 pounds at a cost of ≈$24,000.