If the tank has thick enough material, cut the hole and tap it to match the N.P.T. thread on the other end of the hose barb nipple.
Sometimes injection molded plastic has some good thick surfaces.
2 or more threads in the material would do the trick so long as the nipple/ barb was protected from physical stress like having that part of the tank hit the ground first if the tank is dropped.Consider also, just going to an automotive bone yard and finding a tank from a newer wreck. Even if the tank was from a non injected motor, there will be a fitting that used to go to the charcoal cannister for gasoline vapor recovery. Presto, return connection.