So I'm trying to setup table rate shipping. My client wants to present the customer only one shipping option based on their location. As an example: for x number of items and USPS zones 1-4, they want to calculate shipping based on weight/destination. However, for zones 5-8, they want to charge a flat rate. I've tried the Matrix Rates extension, but it seems to require that I put in the rates, when in reality, I need it to ask USPS for the rates based on the correct shipping method.
I have also tried Webshopapps Zone Table Rate extension, but I can't get support from them beyond "refactor the extension because it's old and it may not work." The whole idea behind using an extension is to not have to write the module myself.
Does anyone know a solution for this?