The main reason I want a 40 pound generator is to charge the backhoe and big truck batteries without having to remove them or to help start them in cold weather.
About 15-20 years ago Coleman came out with the first invertor generator I ever saw. The really neat thing is it came with a quick connect set of jumper cables that put out IIRC around 80-90 amps of DC to quick charge a battery. I used that feature far more than I ever used it to make AC which IIRC was around 900 watts.. Usually a minute or two would bring a weak battery up enough to start a vehicle. It was also a 2 stroke and weighed maybe 30-40 lbs, again IIRC.
Unfortunately a few years ago I went to use it and couldn't find it...to this day I have no idea where it went, although I have a suspicion I can't prove