Paying for public campgrounds

We always pay by check in an unattended iron ranger. Case in point, two years ago we camped at Wilderness Gateway along the Lochsa River in north central Idaho. A friend was a CG host at a nearby CG and let me know, after telling her that our check, written 6 months back, had not cleared. She said theives came through and busted into the iron ranger, ripping open all the envelopes and taking only the cash, leaving checks all torn up. Sadly that was a free night for us and at such a nice campground. I would gladly pay for that night if we ever went up that way and met with the ranger. FS has a small budget to keep their CGs nice.