adding tail weight to balance your plane "before" you fly is the right way to go. i use a great planes center of gravity machine for my setups. they fly pretty decent right out of the shop. if you prefer to cut the covering open to hide the weight , it is your choice and it is also the best way to do it for sure once you've determined that you've found the right setup.. just make sure you attach it securely inside there as well. you dont want that weight coming loose while flying...oh man. the dago is a good looking plane. it'll be a fun flyer . is the wing mid or low? you must be past the trainer stage at this point. best of luck.