RE: Hopper Tank Fueling
When you say "hopper" tank, what do you mean? You're not talking about the type tank that goes in a car or truck, are you?.
If you use a fueling valve, you can hook it to the feed line from the tank to the carb, as the valve shuts off the line to the carb when the fill line is hooked to it. You can also use a third line with a separate clunk to fuel and defuel.