Also spent a lot of time in the industry (drywall, lath, and plaster).
Key cars top out somewhere around 750 pounds of capacity, and I could early blow through that with brining materials to a job site, or hauling stuff to the dump.
Key cars are cool, but you also need other solutions in place for materials delivery and hauling. American trucks are kind of a one size fits all approach to construction. Your truck for heavy hauling is also the truck you use for light hauling.