You are fine just smoking on the standard racks. Nothing wrong with rib racks but if the ribs get 'super tender' they could tear and fall. Try smoking just 2 at a time till "nearly" done. This will keep them firm for reheating without falling apart. The reheat should finish them off. For a good bark, try brown sugar. Also, before sealing, maybe you can cut them into 2 to 4 bone sections for easier handling.