cardboard is larger than the body so it wont clip whilst connected to a single bone. if you want it not to clip you have to play with weighing from multiple bones to bend with your player. it may be time to chose your character creation process. i use iclone you can import your character and clothes models and it will weigh everything for you. export that as fbx import to ue4 export fbx import to blender delete all meshes besides what you want from each and the extra root export fbx bam