probably a silly question.... does a 21 year olds ordinary car insurance cover him in any way if he "borrows" a landrover....... not only are some companies not including 3rd party cover on borrowed vehicles.... im sure some are limiting it to cars...... same thing if you borrow a large van, yer normal car cover wont apply.
yer own landrover insurance dont include any cover for hiring out either.
in short if you want short term hire go to a hire company who will arrange proper insurance.
the op would have been better off offering one of us a free days shooting.