I've got a proper Thatcham Cat 5 VTS rated tracker.... on my motorhome.

The 'black box' was surprisingly small, but would still be quite difficult to hide on a bike.

It costs circa £150 a year to maintain the subscription and was iirc £500 to fit.

Because it's CAT5/VTS mine automatically flags up at the monitoring centre if it's driven without a driver card present... but once it's in theft mode the app locks you out so you can't track it (to stop you tackling the thieves), but the monitoring station can remotely deactivate the engine, but only with approval from the police (ie they can stop it from starting if it's parked up somewhere). It's tracked using GSM/3G and is a service provided by Vodafone.

I wouldn't normally have bothered, but being Transit based (the most easy to steal van in the world) none of the motorhome insurance companies would touch me without it.