rigged this up last week and will be trying it out soon:
This one can apply downward pressure on the spike instead of just gravity to hold it in place.
It works great, I combined it with a Anchor wizard reel.
I used it extensively on my last video on youtube, I don't show it but you can hear me drop the rear anchor spike. When I use it in lakes or rivers with a soft bottom it does not need any down pressure, the gravity drop is enough. If you guys are interested I can make a video of my setup.
I don't have plans but if you google DIY power pole there are tons out there. It just uses a PVC junction box you can get from Menards for 10 bucks and a 3/4" 8 foot fiberglass spike.