I am using a third party fulfillment software (Shipstation) to print my labels and pack lists. I use USPS flat rate packaging for 1lb or less in addition to UPS packages for 1lb or more. Since I don’t need to print labes in WooCommerce, but I DO need flat rate packaging, would I need this plugin or the USPS one? Are there any significant differences between the two other than the ability to print labels?