Rock Jack Raised Bed, Pond Filter, and other ideas for a heavy box of rocks

I am building 4ft x 4ft x 4ft rock jacks for my gate posts on a 6ft x 12ft gate that I will see every day as it's at the entry to the house. As I move an immense amount of rock (at least a ton for each jack), I am thinking about how to best stack the functions of this feature of my property. I have considered a raised bed in the top ft of the jack box, but this would reduce the life of the wood (salvaged old growth doug fir and redwood). I also think it would be a good pond filter if I fill in the large rock with gravel and sand, then pump up the water through with a trench/culvert under the driveway in between. Obviously, this would also reduce the life of the wood. At the very least, I will use these rock jacks as thermal mass for heat loving plants like grapes or subtropical vines (we are in between zones 8-9, at 1700ft). Any thoughts on the idea of a rock jack raised bed or pond filter?

Here are some pictures from a few days ago during the building process.

Hi Ben;
Nice looking place you have there!
Have you considered using field fencing to help wrap your rocks?
As your wood rots away the wire would keep the rocks from falling out?

I've seen many corner posts that are surrounded by wire wrapped rock.  They seem to last a lifetime... of course I'm not dead yet so maybe they will fail before then...
Then we could say they last, Almost a life time!

Maybe put a green roof on top of them?
I'm thinking a roof deck with decent overhang with a layer of plastic,  topped with burlap bags,  held down with soil,  planted with bunny chow.
Build a boarder of wood around the edges,  to hold the soil in.
The  roof protects the wood of the rock jack, the soil protects the plastic from decay,  the greenery protects the soil from erosion, the height of the jack defends the greenery from some predators.

Thanks for the replies, and good ideas. I may have been wise to have wrapped the inside of the boxes with fencing, but I leaned towards making it look prettier. I am thinking I will try to accomplish some of the same benefits as fencing and a green roof. I am thinking I will do this by filling in the spaces between rocks with sharp river sand for the lower 3ft, then woody debris and compost for the top foot. I will then plant grapes in the top with a cage of cattle panel up to the height of the gate to keep in  my LGD who can jump anything short of a 6ft fence.