How big is the rubbermaid container?
Most likely one should be enough if it seals well. That is assuming you are using the full size packet and not one of the small ones that vendors sometimes use for shipping.
Also, I have never heard of seasoning a piece of plastic, maybe that was a joke.
If the container seals well and you do not open it that often, I have had a Boveda packet last over two years in a piece of Tupperware.