Safe practice is to have a fuel 'day' tank, usually a 6 gallon outboard tank. If you had a fuel leak, you would have less than 6 gallons to clean up, and a potential fire would be limited. You should never let the engine run more than a couple of hours without 'making a round' on it for safety reasons. You should shut the engine off and check the oil once each day, so top off the fuel at the same time. You can fill it from the storage tank(s) by gravity, pump or container, depending on how fancy your power plant is.
The injector return should go back to the tank to reduce the chance of air bubbles in the fuel injector pumps, although some people run the return into the fuel supply line without problems.
The outboard tank comes with a primer squeeze bulb in the fuel line that can be very handy for priming (removing air from) the injectors. It has a carry handle like luggage,a fuel gauge, a good cap with a closable vent and can be taken in a car to the filling station. They are cheap at the sporting goods / boating store, better at yard sales...
Your large fuel storage tank(s) are great places to mix your favorite brew of biodiesel, veggie oil, old crankcase drippings etc.. Maybe one tank of clean diesel, and a tank for 'experimental fuel'. Lots of fuel filters is good.
Emergency fuel shut off valves (solonoid or manual) are good.
Fire detection, low oil pressure, and high jacket water temp shutdowns are good. They can be connected to the fuel solonoid as well as shutting down the fuel injector rack.
Scott E