I removed the existing sealant to install eternabond (although it was not silicone)and cleaned the area well, even using the eternabond pre-treatment--to remove the existing sealant, I mostly scraped it off with a plastic scraper. I bought the metal roller to press the tape into position.
I still had a few bird's mouths and wrinkles so had to slit them and retape in places. I did the roof and the rear seams and all the lights.
Eternabond is available on Amazon as are the caulks. I used 4" and 2" and double sided for some of the lights. I bought the materials originally from a roofing supply company and they called it "miracle" rv tape. It has a finished top, there is also a tape that has a paintable top which I used for our awning. But the repair didn't last because the awning just tore elsewhere.
I have not heard of eternacaulk but would like a way to seal the edges. The tape does pick up dirt, but it also cleans reasonably well with a little scrubbing. I would rather have unsightly tape than a leaky RV.
I have used sikaflex and dicor but don't have much insight into the differences. Also used ProFlex but it hardens in the tube easily and has to be used all at once.
Good luck with your repairs! It does seem like your rig is young and shows how any RV can get leaky even with lots of attention.
