I would go with standard coon size trap. Take it to car wash and really give it a good spraying/wash. Then two pieces of carpet one draped over trap creating a 'secure environment". Second piece cut to fit inside trap covering wire bottom before pan, small piece to go on pan and another small piece for wire bottom beyond pan. Now for baiting. Place a piece of Mylar or feathers or even a ribbon (anything that will move in the breeze) hanging beyond pan as a visual attractor. Then LIGHTLY sprinkle some catnip on carpet leading to pan and a good amount of catnip placed on piece of carpet that is on pan (let it rub it's head on that pile). With all the heads you are being left seems like food isn't a big issue for this cat so use the visual attractor to peak it's curiosity and the catnip to feed it's addiction may work better than food.