24 hours later
... could not stand to have this as an open loop, been churning - this is what I have:
If I think in terms of pure GTD - then the status reports are simply another task I have to do.
An item arriving in my inbox, whether informational (and destined to be filed or deleted), or actionable, also comes with the additional actionable task of "update the customer report". Since this is ALWAYS going to be under 2 minutes, I guess it is just my tough cookies, it is my job to be updating the customer reports as information flows through me. I can tell myself that this is why I get paid.
So the answer I have come up with is to keep 2 sets of books. Constantly update my customer's status reports as I do my processing (always < 2 mins per item... more like 25 seconds).
This way the reports are always in a state to be sent to the customer, and they are NOT part of my GTD system, not part of my weekly review, not confused with gtd in any way.
At least this way I have clarity and no open loop, just a bit more labour to do. I can live with that.