Arduino Power over Ethernet (from a distance)

Ok, so I have a Arduino Nano with a humidity/temp sensor and a Bluetooth module.

The whole project needs to be relative small to fit in the plastic in the wall (https://www.yousave.dk/images/billeder/5703302152686-p.jpg)

All I need now is to power the device, and I'd prefer a solution without batteries, unless I get can a year of battery life out of it.

I've thought about doing it over a Ubiquiti PoE+ switch, but I'm very open to other solutions.

What is a good way to power this given that the power source is 5-10m away?

You might be able to use something like this, PoE splitter. Other brands might offer you a smaller size, such as Smaller PoE splitter.

Or, you can set up a solar charge setup with batteries ofcourse.

Or, you can even put in a Li-ion battery - Measure the current draw and you can get the run-time based on the battery specifications. If that is up to your mark.

I don't mind tearing apart an ethernet cable myself for the two DC PoE leads. My knowledge is a bit limited here, but I'm assuming I'll also need some sort of voltage regulator to avoid leading 24V into the Arduino.

Can I use something like this?

https://www.adafruit.com/product/1385

And is it feasible to run PoE over 10 meters?

Solar charge is not an option as it is indoors. I can run 230V AC there if needed, but I assume this will only make it more complicated. The main goal is to keep the size down.

I have a security camera system that uses PoE for the cameras. The ethernet cables that come with it are 100’ long so your 10 meter length will be no problem at all.