We have just replaced all our electrical hookups at our boat club. We looked at power poles like you would find in a marina, but they were way too expensive and would not be able to accommodate a flood.
We settled on 1'x2' white meter boxes with an RCD and a meter inside and a 16A blue socket mounted on the back. These were fitted to 2 pieces of steel angle, concreted into the ground.
Way cheaper, far more robust and will survive a flood.
You can buy old meters cheap off ebay, some are reset to zero too, I have one on my immersion heater at home to monitor a solar setup. RCD is important though.