Get a monimoto. You can track it and got to it's location yourself
The problem with any tracker is they work only as long as people react and they remain on the bike. And if they've got a signal, chances are in underground carparks there's little to no signal until near or exiting. Same thing happens with certain garages. Stating the obvious, bikes by definition have limited places to hide a unit. Unlike cars where units can be very well hidden. Most if not all current monitored trackers are retro fit, because of size limits where they can be located and on the skill of those fitting them. Fitting several smaller air tag type passive trackers would improve location.
I used to install alarms to bikes. Some, of the so called installations where utterly useless. Plus owners not told/explained/showed all the functions, how to use and their limitations, especially internal batteries. Which lead to many system failures/faults and wrongly in most cases giving them a bad rap.
To install something like Datatool/Meta/Spyball etc would take 5- 7 hours when done properly. Most where fitted in under an hour. The other big problem certainly with BMWs and most bikes made in the last 10 yrs or so is space. As mentioned previously by another, a good place is the airbox on a GS but as also mentioned is the faff it is to fit which would incur cost probably as much as the unit costs if not more.
Most trackers certainly Datatool are just that. They've got no self defence eg audible alarm, warning you its being tampered with. Not until it's either disconnected, ignition switched on with no tag present or moved 50m ish without it's tag being present and then it's by the monitoring company no audible alarm. I know of GSs that have had their trackers removed whilst parked especially in car parks. The scrots know where they're likely to be fitted, especially on a GS. With knowhow It don't take long to get at them, cut remove the unit and push the bike away.
People dressed in bike gear touching a bike isn't really going to attract attention. Until they start with the angle grinders and that's a maybe. Its takes seconds to get through a disc or non anti grinder U lock.
Until insurance companies start applying pressure to have trackers fitted during manufacture, intergrated as part of the ECU, things aren't really going to improve.
The police aren't really interested they're stretched too far as it is. Double the police force then maybe things will improve. Very unlikely to happen. The scrots know that even when caught not a lot will happen!
The best defence is, out of sight out of mind, don't park in the same place every day and physical locks.
Make things as difficult as possible, not easy for places of work without monitored inside the wire parking. Best advice in that situation, get a unattractive commuting bike.
None of the above is going to help this chap. Stable door and all that. But it might help others.