Do you need to sanitize every spring?
It’s good practice after storage, and essential if the tank sat with water in it, or if the water ever tasted or smelled off. The bleach ratio above is a common guideline; your RV manufacturer may give its own.
Why test the detectors?
Carbon monoxide and propane detectors wear out – most have a replacement date printed on them. A rig that sat all winter is the right moment to check, before you run the furnace and fridge on propane.