The sole positive is he can plug a welder into it...
But it's a hell of a lot cheaper to just put a generator in the bed of a real truck. Plus you won't accidentally use all your battery welding and be stuck. Since you can't just bring out a new battery, you'd have to tow it back.
I don't know man, a lot of work trucks can get to six figures pretty easily once you start adding utility beds and the like. Especially if you start with a one ton.