We can work backwards and double down on this problem by making sure it remains inaccessible for as long as possible.
Ideally, you would want to weld the fuel hole shut, but that may be impractical. Depositing a cartoonish amount of very strong glue into the fuel cap cover can be a more realistic compromise.
Attempts to regain access may leave the fuel tank vulnerable where it can then be double tapped with bleach.
I'm not American, so I can't speak to the reality on the ground over there, but I'd say you should try getting rid of that debt as fast as possible.
It sucks feeling guilty about every necessary purchase with that ever-growing number looming over you.
Shit happens. A pipe will burst. Your favourite uncle will have too much fun on a gambling app. The car's engine will make a noise no mechanic has ever heard before. etc etc.
I have roughly ~$3.5k in debt and it feels impossible to shake off.
That being said, there's no 'wrong' choice. The other two comments hit the nail on the head. These aren't the only three options and you can always go back and give another shot at whatever you didn't pick.
stop smoking marijuana