Not sure where the water came from that rotted the back end of ours. I suspected the middle rear brake light but I eternabonded all of the lights both rear and cab front. I didn't disable the running lights but cut donuts of eternabond and hopefully eliminated the path for water intrusion.
I have more pics of the process on my photobucket site:
Rear RepairWe did take the RV far and wide in Arizona but Colorado is more challenging road wise. I do have some great suggestions from a Roads and Routes post so more to explore! Being a rockhound or a telescope expert would be great. We just love to hike in remote spots.