Securing spare wheel

I just have an ugly steel rim and a 1/2 dead tyre.

I used to have a padlock through a bolt hole and the carrier. A ring of bike inner tube over the keyhole kept the dust out.

Spare wheel cover and thats it... If they want a wheel it tkes 60 seconds with a jack. or 60 seconds getting the cover off.

Why don't I lock them up?

4 occasions when out bush I have had :-
1 friend with no keys to the lock on his BT50 spare locked under the tray.
1 friend no lock on the spare but lock nuts on the wheel with no keys.
1 friend who though that a spot of weld would stop the buggers nicking his spare off the carrier, stopped us for quite a while too.
1 friend who didn't carry his wheel winder key (100 series) incase someone broke in and used it to nick his spare.... Bolt cutters and then spare on the roof rack.

I'm a mae and I have enough troble finding the bloody car keys let alone locks for various things.