auxiliary fuel tank for diesel truck

I had similar concerns years ago with my 06 Duramax and it's 26 gal tank. I really, really wanted an extra diesel tank. Finally decided to just carry a 5 gal jerry can and a siphon hose in case I really got in trouble. We need the bathroom breaks every couple of hours anyway, and I decided for me it was just another toy (I like toys).

I'd rather have the tool box room instead of surrendering it to an extra diesel tank. Also a little worried about ending up upside down some day with diesel dripping down my neck and something nearby sparking.