We use a bootbag on the rack and stuff more into the "luggage space" behind the seats in smaller bags.
Passenger footwell is sometimes used too!

likes to take the kitchen sink!
If expense is not a problem there is a "Mogbox" to be had that fits onto the rack. and is lockable....someone here can get the details as it was in another topic recently.Also the Mulfab footwell box.
Hillsalive bespoke fitted luggage.
Enjoy the tour and many years of driving.