Is the unit being left plugged into a 220 AC supply socket ALL the time?
And is the power supply to that 220 AC socket being switched on and off intermittently as would happen on a boat or RV which is sometimes plugged into shore power?
Or is the unit being used normally in it's covert unplugged mode and then just getting plugged into the 220 AC occaisionally to recharge the battery?
I don't have an electrical diagram for that unit, but if you are not using the device covertly, then one possible solution is to have the tracker plugged into a PORTABLE POWER SUPPLY (power pack), which is in turn left plugged into the AC mains to recharge when necessary / possible.
Here is a link to a Duracell brand 600 watt portable power supply although there are certainly many different brands / models available:
This type of portable power supply could probably power that small tracking device for weeks at a time before needing to be connected to a live AC power supply again to recharge. The power pack could be left plugged in even if the AC was shut off, and the tracker could be left plugged into the power pack. That way the tracker would always be powered by the power pack and could be left turned on all the time with no need to switch it on or off.
It would obviously not be a totally covert setup, but could at least be partially concealed on a large boat or RV which might work well enough if that was your intention.
I realize this is not the type of solution you were originally looking for, so feel free to click on the NOT HELPFUL rating button and another expert will automatically take over and hopefully be able to help you with a better solution.
Good luck and take care.