Charging using the truck would require running the truck all day -- probably not an acceptable alternative. Consuming 2-10 Kw from a 200 Kw engine would be so inefficient that it'd be too expensive anyways. Instead you'd need to run a generator all day charging batteries.

A fast charging, high capacity tool battery takes at least 60 minutes to charge. In high power applications (lawn mower, leaf blower, chainsaw, etc) those batteries might be emptied in a little as 15 minutes.

A better alternative might be corded 240v tools running directly off the generator for high-power applications. 120v tools are limited to 2-3HP which doesn't compare well to gas engines.