Implement a way to manage "Bill Me Later" and Offline payment workflows

If I want my guests, hosts, or sponsors to be able to pay offline (such as, by check), then I need a clean, user-friendly way for them to

• select “Bill me later” at checkout

• see clear instructions for how to complete their payment offline

• see clearly on my event payments dashboard which payments are “pending” and require follow up

• easily mark which payments are fulfilled (as well as, how they were fulfilled; such as, by including the check number)