The real equivalent of a kei truck in the US I think is a minivan. I see a lot of blue collar workers that use an old beater minivan as a work truck basically. Its an easy engine and platform to work on; something like a honda odyssey shares parts with a civic and most anything else they made in the same era. There is a ton of space when you take out the seats, that locks up unlike a truck bed. The floor is a lot lower than a truck bed which makes it easy to load stuff in and out. You get much better gas mileage than most commercial van platforms. They sell for a few thousand dollars in decent shape used and hold their value.