I want a combined outdoor setup and planning to take BaseBox2 and to put RPi ZeroW in its "free pocket" -free space where the G-LAN and USB ports are.
I am planning to buy one PoE Splitter to extract the power from the UTP cable for powering RPi.
My concern is, if this PoE Splitter will "leave" some power inside UTP enough for powering BaseBox and will it interfere the data passing through UTP cable? Offcourse, data is only intended for BaseBox. Length of the UTP will be approx 10-15 meters.
Is it going to work?
I think (hope) yes, but I would really like to have some expert/more experienced opinions because my previous experience with PoE is only through powering one of mines RB951G in my flat and this is nothing complicated compared to this.
Tnx in advance

The BaseBox has a USB port that can be used for power, so why use a splitter?

I've used this before to charge devices in the field during testing. Worked well.

Hi and thank you very much Zaffo for your suggestion!
I did not provide enough info in the first question (apologies!), but the USB port is going to be used / occupied with 4G LTE modem (IK40 specifically) that is going to be WAN default gateway, so there is only an option to put some usb hub and power RPi with that while also connecting LTE modem in the hub and not directly to the MTik USB port. But I am little bit afraid of such a solution because I thing those hubs can be little bit tricky, so I hope that there exists better solution using PoE and "dividing, separatring, extracting..." DC power for both the BaseBox2 and RPi in the same time.

I do not need data through UTP cable for RPi (it doesn't have ethernet port at all, only wlan) so my main concern is how to extract little power from UTP to power RPi while not interupting/interfering power and data for BaseBox. What comes to mind is some "non professional" but maybe feasible solution to use a 100 Mbit/s PoE injector instead of the default 1 Gbit/s one and only utilize 100 Mbit/s LAN speed for BaseBox while leaving 2 twisted pairs in UTP just for DC power and then solder some extra wires at the end of the cable to get (extract) some DC power for RPi with additional step-down adapter from 24/12V to 5 Volts that RPi needs. I am afraid that such a solution would be problematic (interference) if one wants to utilize full 1 Gbit/s LAN (all 4 twisted pairs for data) but maybe with 100 Mbit/s can be acceptable, at least if there is no better solution. I would really like to hear comments, critics and especially suggestions.