I see B2B KIng provides a Purchase Order gateway, but there doesn't seem to be any ability to allow the customer to upload a purchase order document when ordering. Ideally, we'd like them to enter the PO number and then upload a .pdf or similar of their PO. It would be ideal if we could optionally force them to do this as part of the PO payment gateway.
Is this something you are planning to introduce or can you suggest a way to achieve this?
This plug-in seems to offer the ideal implementation of this...
https://codecanyon.net/item/woocommerce-advanced-purchase-order-gateway/20743713