Yes I agree the most you can do is hide your luggage or, possibly put a chain and padlock through all the baggage handles. On my rack I use a flexible cycle lock through the case handle and rack. Deterrent if nothing else.
1969 4/4 1995 plus 8 1996 Plus 4 4seater 2002 Aero S1 2013 M3W 2014 Plus 8