I'd pack enough clothes for 5 days max as you'll find it's so much easier to wash each day.

Depending on what grade of car you've booked beware of taking Large Luggage as the boots/trunks are really small. Some Intermediate/full have boots which go under the seats but the max you can get in will be either 2 or 3 depending on the size of each case/holdall.

If you need another holdall then you can get them from the Flea Markets on 192, the one where I go by Marker 14 sell them for $7 and packed work under the 23kgs. The bags are light so no extra weight is lost.