I got pretty involved with the one I put on my last toon. Experimenting as always. Some of it worked pretty good! This shot is of the ten foot pole running thru the hull into the lake bottom.

I didn't want to add even more lightning rod to the boat so I chose two schedule 80 pvc conduits. They nestled together so tightly that I had to lube and drive the inner one in with a sledge hammer. Made for an extremely strong and fairly light pole. It also doubled as my flag pole
Further details: I built this with the purpose of 'pinning' the rear end of the boat so the wind wouldn't bring it around when I was beached. It saved me all the tedious work of two anchors on land and lines off of each rear corner. It was a great timesaver. I could just land the bow and hop back, pull a quick 'hitch pin', and drop the pole down. I usually didn't even need to put out a bow anchor.
I originally set it up with a modified RV tongue jack (powered). You can see it in the shot. This part of the build didn't work worth a crap. My thought was to DRIVE the pole into the bottom. It sort of worked but made the boat kind of rock on a 'pivot'. So I quit using it and let the pole ride up and down in the guide tube like a dock collar.
It worked well offshore as well in the shallows, but only in soft bottoms. Wait, that didn't sound right
I also used it on the rare occasions that I slept under anchor in deeper water. I would drop the pole and just let it hang there. If I had anchor drag, the pole would hit land before anything else. Fortunately that never happened.
I still have it. I'd like to remount it on my new build, but haven't given it much thought yet. Not quite sure where it would fit.