So I got this working but I have one problem. I am getting errors when selecting Priority:
-2147219431DomesticRatesV3:clsRateV3.ValidateContainer;RateEngineV3.ProcessRequestInvalid container type. Valid container types for Priority Mail are Flat Rate Envelope, Sm Flat Rate Box, Md Flat Rate Box and Lg Flat Rate Box.1000440
I think it has to do with the package type. How can I tell it to use one package type for one shipping type vs another?