Read an article recently where a much higher proportion of passengers (proportional to build numbers) have died in Cybertruck fires, than the Pinto. ...
They probably couldn't get out. That was really a bozo move to make the interior door handles electrically operated (I know there is a manual pull). 5 people near us burned up in a car/tree hit on a model S.
Back to your spare fuel tank, if you DO put in a spare, be real sure you do a Pro job installing it with quality line and fittings. For your own safety.