It is work, but you should consider putting chicken wire fencing under the porch. You can do it behind whatever latticework or posts there are, so it isn't as visible or unattractive from the street, but it will keep the cat from getting in there. It also keeps out skunks, coons and other critters who might decide it's a good hiding place, and keep Cam out of there, once he's old enough to think of it as a hiding place.