Rewire Tracker Install

Hi everyone. New here.

I have just bought a 2013 Baby RR dynamic SD4 and want to fit a tracker. I'm semi competent with electrics and wiring and used to install a lot of ice car entertainment when I was younger.

I have just bought the DB1-Lite tracker from Rewire (not a bad company, i have one of their battery mobile ones on my bike and works well)

I have also bought a relay to fit inline to the starter motor so that I can, should the need arise, cut power to the starter motor meaning that anyone trying to start the car again, can't.

Can anyone give me any advice as two where to fit this unit (I was thinking behind the dash) and also where I can locate a suitable positive wire that will cut out the starter motor for the example above? I know the fuse is under the bonnet but wondered if its all been done before and if people have found better was of doing things. Say for example chopping into the start button cables (four of them) meaning that they can't start the car that way.

Thanks, Steve.