I'm using secure warehouse quite a bit. Most useful for pirates collecting booty on a number of hatch breaking missions, then unload all of it, one trip to a starport (or get someone else to do it for you by pricing them out as a profitable trade).
There is a mostly legal use for secure warehouse too, especially if you're collecting materials, and this is what I'm doing. Same thing as above but added hatch break and collectors to my bounty hunter. So interdict them, KWS them, hatch break them, destroy .. then collect bounty, materials and cargo. Most of the money comes from the bounties but materials come in handy and some of the rebel transmissions, military plans and trade data packages are worth a bit, and add up once you've got 50 of them. Collecting toxic waste is just for fun.
I'm not sure if you can pay fines with a redemption office by the way, not you own anyway and not if you're in the system where it's issued. I can't. Maybe from a different system or ship, not sure but it is a redemption office first I think, not a full on interstellar factor. Can reclaim bounties though and better than a factor for that, I think (at most) half of the 25% transaction fee goes to the carrier, so even worst case you beat an interstellar factor's 15%.