The GPS chip could be dropped into the saddle tube. There are dozens of mfrs. of these chips designed to locate "lost" property. Programmers should be able to have their cloud dump data into your cloud so that the location of the bike at any given moment could be known. A rental shop could go to the police with a BRM printout showing the bike has been at a specific address for X days and is your property. A hard copy printout of the info would be a far more effective tool than looking at a screen from some phone app.