We often leave the car for up to 2 weeks. Choose a residential area. Not outside someone's house. Preferably a parking spot where there is no pavement so that people have no reason to walk past.It is always a leap of faith leaving your car. I once left it on a busy road in Newquay where the road narrowed on a bus route (only one car can pass at once so plenty or mirror room and outside an old folks home so strangers cars commonplace.It was fine.
I am taking a sabbatical next year
The first trip will be Glasgow -Ardrossan -Inner Hebrides, Hebridean Cycle Way, Ullapool, Cape Wrath, but not sure after that. We have 4-6 weeks.
For this trip, full camping gear, one touring bike and a fully loaded big dummy cargo bike so the dog can come (sits in the back), we will use one way van hire. Manchester airport (near me) to Glasgow airport (near Ardrossan). One quote came in at £35