My dear chap, you simply need to secure a stout rope to the rear bumper of your 'Ute Truck' & toss it over your roof from the other side of the house; instant security.
However, you may wish to disable said vehicle in a major way, lest your Sheila should fancy popping to your most adjacent shopping Mall to purchase a pair of Kangaroo-skin Manolo Blahniks, whilst you are perched upon said roof (don't tie yourself on........)
HB