There are several ways to do this. Your best bet is ultrasonic from the top of the tank but those sensors, that are of good quality, aren't cheap.
Do you need analog level sensing? If you could just have 4 set points (F, 3/4, 1/2, 1/4) you may be better off not dealing with anything analog and just use discrete capacitive proximity sensors. It would be cheaper likely too.
Many times you can sense straight through the tank wall horizontally.
If you're hung up on analog like I said you can mount it to the top of the tank as long as the tank doesn't slosh a lot.
You said Kerosene... If you're actually doing gasoline/petrol its a completely different animal and should exercise more caution.
Here is an example of an ultrasonic: