The real world isn't Hollyweird. Cars and trucks don't go "BOOM" and burst into flames in most accidents.
It would take an incredible side impact to rupture the tanks, then you would have to have an ignition source, then you would have to be incapacitated where you couldn't escape....
Not impossible, but unlikely. You could always put a cage of steel bars on the outside of the tanks for added protection.
For a comparison, look at all the Stovebolts with gas tanks inside the cabs that have had no problem.
Caveat: I personally know of a fatality in a F**d with an in-cab gas tank. Cap came off in a roll-over and a little girl died.
Nothing is fail-safe. Common sense precautions will protect you in 99% of wrecks.
