Where would you install them on the bike where they couldn't be removed easily? I've thought you could place one in the frame, but that would be difficult to do aftermarket and the GPS and WWAN antennas would need to exit it somewhere.
Shaft were the seat affixes, maybe use the frame as the antenna - dunno, was more interested in what is out there already in a way that is respected enough for insurance companies to make a difference. That's the true test of a security product - how much of a discount does your insurance get for having it ;).