Most RV Roofs are sealed with DICOR.
They make it in a self leveling variety for roofs and horizontal application an a NON LEVELING variety for vertical application.
That said, ETERNABOND TAPE is also used as a nearly permanent solution and is what I will be using this spring once the temps get above 60 regularly.
Preventing water from getting in your camper is the single most important thing you can do to prolong it's usefulness. Most campers die and go to the junkyard or get traded in to a dealer for $500-$1000 once they have significant water damage.
Search YouTube for either of those and you will learn all you need to know about roof inspection and repair.