I think you have to assume that cars left overnight are not safe anywhere!!!!!!!!!!
Recently, driving back from Scotland, got pulled at a police roadcheck looking for gangs of East Europeans out of Glasgow that had been targeting cars parked overnight.
They advised when leaving your car anywhere that you leave no valuables and DEMOSTRATE that the car is empty by opening dash compartment and taking hatchback parcel shelf off showing nothing in the boot.
On my quest for munros I tend to go to Scotland for extended periods, I have to take a lot of gear for walking, climbing, camping, cycling and I am often forced to leave my car overnight in vunerable places.
My tactics are to use one of our mountaineering club huts as a base and go out for single/multiday trips. On single or multiday trips I only take minimum gear required for the specific objective(s) locking the rest up safely in the hut, have been demostrating what is in the car (usually nothing) when I leave it, for decades.
I then return back to my base for rest, wash clothes, cook some proper food, plan the next trip etc.
When I leave my MTB in the middle of nowhere, I remove the wheels, hide the frame, then hide each wheel in seperate places in the first 200m along my route.