I really think you would be happy using the
Thule 400XT Aero complete roof rack base system and
Thule 866 Escape II roof bag setup. No matter what gear you plan to carry on your roof, you will need a multi-purpose roof rack base system. The Thule 400XT base rack system includes four 400XT Aero Feet, four FitKit 2119 Clips (these clips are specific to your 2007 Toyota Matrix) and twocrossbars. You will attach the clothing / camping gear carrier to the 400XT Aero front and rear load bars. The 50 inch bars are the recommended length for your 07 Toyota matrix roof top. The Thule 866 Escape II roof bag attaches directly to the Thule 400XT base rack load bars. This is an excellent cargo carrier that offers great carrying capacity for clothing, camping gear, sleeping bags and more. It is the only roof bag that is truly waterproof and quickly removes and folds for easy storage when not in use. Has an astounding 15 cubic feet cargo capacity.