So it took some doing, but I finally have created a working solution from start to finish that creates and edits purchase orders inside of SAP.

The biggest issues I found going into

it was the amount of data I needed to pull in to populate things like “Purchasing Org” or “Company Code”. There was another zpack available that lets you pull out all the values for these fields so I could stick them in a select list, but there were probably 6 or 7 of these calls to make to get all the necessary data populated.