Thanks. I've got a friend who has owned a Roadtrek ..and inspired us to get one..I agree with you that cracking sidewalls are a dead giveaway... but, rubber gets fatigued over time... As for Centennial, here's what I got.. I understand that the 6 volt AGM batteries are superior. They are located under the front hood.
I plan on getting solar panels installed on the roof, two 160 watt units integrated into the charging system. I have a great installer for this, but, realize that it's still roof penetrations...
https://battsys.com/centennial-battery-cb6-224-6-volt-224-amp-hour-sealed-lead-acid-agm-battery