I still haven't figured out what the big deal with having the fuel tank in the cab is.. I suppose if you need the extra cab space it makes sense, thats about it.
If the tank is solid and not leaking or rusted, i'd think the cab is the safest place to have it.. don't they put the gas tanks in race cars in the passenger compartment for saftey?
If something hits that old truck hard enough to rupture a solid fuel tank, then you won't be alive long enough to enjoy the BBQ, anyway.