On 31 July 1998, “Joseph Camp” encouraged case officers to find their own solutions to forensics-related and other problems, but listed a few “high points” from a tradecraft manual that, as of 1998, was intended to be a part of Delta Green: Countdown (1999) but which has since been published elsewhere, including Delta Green: Eyes Only (2007). This article is a reprint of Camp's message to the DGML:
Firearms
We strongly encourage agents to use weapons that aren't registered to them, and dispose of them after an op if the op required gunfire that drew police attention.
Expenses
We have a number of credit cards issued to paper individuals - people who do not exist except in documentation. These cards are circulated among COs as needed for ops. SOP is to make a sizable cash withdrawl from the card at the commencement of the op and to use the cash for all transactions. The funds…well, that's a long story. The short version is that over the decades, we have accumulated a sizable number of forgotten black-ops bank accounts. Invested shrewdly as the years have gone by, the funds have become substantial. And yes, the occasional $500 hammer helps out, though indirectly - agents in agencies who buy such hammers tend to know how that money moves around, and can dip into it under the guise of their normal duties.
Paperwork
As a rule of thumb, we either have someone at the agent's employer who can rig the paperwork, or we have someone at another agency who can rig the paperwork on their end to have the agent detached or loaned out to that other agency, when in truth they're going someplace else altogether.
Keep in mind that in the real world, DG as a whole rarely handles more than one or two ops a month, sometimes none. Many agents don't have a single op in a given year, but they do other tasks such as digging up information at their employers or doing other such legwork. Our special sorts of situations just don't come up all that often, and we therefore can make them happen with the same limited set of resources.
In your simulation exercises, you may have a much higher rate of events and a correspondingly greater need for infrastructure. And note that an "op" as defined above means a single short-term assignment. Some "ops" last for months or years, with numerous minor incidents along the way that can be handled in the course of the agent's normal duties, with only occasional need for a full-blown paperwork shuffle. And generally, at least one agent (or at least a friendly) on a given op really is there for official reasons; it's the others who he brings in that are there under false pretenses. In such cases, the "legit" agent can generate all the paperwork through his chain of command.
Finally, don't underestimate the point made in the DG sourcebook or by a poster in this thread: when bureaucrats are told what to do by someone who seems to have the proper authority, they do it without thinking twice. It's just part of the daily routine for them. A dozen conspiracies cannot match the innocent sweeping-under-the-rug efforts of a single overworked paper-pusher who can't be bothered to read between the lines.