Gasoline smell in cab

[70ChevyCST]

Hi guys,
I already did a search on this topic here and read "Fuel Smell in Cab" by spdrcr29 in March of 07. There seems to be no consensus here...about half said it's normal because the gas tank is right behind the seat and the other half said check the sending unit gasket, vent connections, filler cap etc. Well I have a newly frame off restored 70 CST-10 fleetside longbox and the seller left several bugs for me to swat. The next bug for me to squish is this gas smell problem. I do not want to move the tank. I've inspected behind the seat carefully and have seen no signs of seepage...There's a new tank, sending unit and cap. There is no vent on this tank which surprises me! I'm thinking there's a new sending unit gasket if there's all these new parts here....but I will obviously check this now...But here's my question: In the LMC parts catalog I see a cardboard tank cover and a tank cover carpet are available. Could this be why I'm still smelling gas? The restorer did not spring for either of these items. Also: The tank is still bare metal. Should it be painted? Oh yes...smell is worse when tank is full. Thanks everyone in advance....
Bob