Your talking about re-doing the caulk and not applying a sealer product to the roof material right? For re-doing the caulk, seems quite a few place Eternabond tape over the caulk. Then you don't have to worry about the caulk in the future. I've thought about doing it to my camper.
2017 JayFlight 28BHBE
2014 JayFlight Swift 264BH (Sold)
2007 GMC 2500 Sierra Classic Crew Cab LBZ Duramax / 6spd Allison