Great episode, to youre update Video:
I would close the hole for the extra tank.
Keep the tank but hide the filler somehow.
My grandfather had an extra tank and as soon as the normal tank was empty he could open a valve and the fuel from the extra tank would refill the standard tank.
So you dont have the problem that you dont have any indication on when the extra tank is empty.
I dont know if you can fabricate that or if its even worth it for youre needs.
But keep the 40 outside stock looking at any point...
I would close the hole for the extra tank.
Keep the tank but hide the filler somehow.
My grandfather had an extra tank and as soon as the normal tank was empty he could open a valve and the fuel from the extra tank would refill the standard tank.
So you dont have the problem that you dont have any indication on when the extra tank is empty.
I dont know if you can fabricate that or if its even worth it for youre needs.
But keep the 40 outside stock looking at any point...