Yup, remove it completely. Seal every joint carefully. You can wipe off the excess right away for a good look. Putting sealer on the outside don't work. Look at an old camper, people keep putting on more layers of sealer hoping to stop leaks, looks like crap and don't work. Been there, done that. Clear silicone is not the way to go, get lifeseal or 3m 4000 .