Maybe I am missing something key in the documentation.
I need to pull a list of saved addresses a customer has in my MODX site prior to the Checkout page loading. With JQuery, I am going to process these into a typeahead select box so that the user can choose which of their saved addresses to ship the order (no MultiShip, each checkout can only go to one address).
Some clients have a lot of addresses, so much that it errors out any attempt to make a cookie of the addresses, so I cannot pass them through cookies.
How do I pass the array of addresses as a hidden custom field using a PHP endpoint? I see how to check Authentication in the SSO php endpoint, but I am having trouble figuring out how to send along the custom data from a PHP script.