You kinda should like nothing I say will persuade you, but here it goes.
A tractor is bought and paid for, so to say. It'll only emit as much as you put into it. Where as with a hover-cab, before you get to theoreticaly use zoro-emission fuel, you first have to make it. I.e. digging up and smelting rare metals, shipping parts all over the world and churning them out in coal-burning factories.
You'll be dead before your tractor catches up the starting costs.