Typically you are laundering cash; electronic systems do not help here since all the means of depositing the cash into the system are monitored.
You need someone who can safely pass your money from paper to digital. The only people who can do this are folks with substantial paper money flows. Think cash-only restaurants. They report a modest growth in business, deposit your cash, and "buy" goods and services from you. But you can already fake this as a restaurant supply vendor.