why would it use more fuel my truck has a 200 amp alternator its spinning all day anyways and 1300 watts at 12 volt is a little over 100 amps. Even when idling I gotta run the PTO so it doesn't shut off so its always making electricity. on top of the 4 giant deep cycle batteries each holding lots of juice as well.
I find it hard to believe that using the electricity is same amount of use as not using it.... I could be off on it that just seems wrong. But either way you really don't want to run around with a miner in your truck what will you do with heat exhust? Or bringing in new air?
And biggest thing is it worth it for your employer to possibly catch you and you lose your job? So seems like it would be not very ethical, and big chance of losing job if caught.