I have a Topeak Trunk Bag and I love it. It includes a shoulder strap so you can use it as a walk-around camera bag when you get to your destination. You should have no trouble mounting a regular (non-beam) Topeak Rack if you have eyelets by the rear wheel. The eyelets probably aren't threaded so just use a M5 screw and lock-style nut through the eyelet hole. Use Rubber P clamps to connect the rack up top.