Ok, just finished sealing my windows and vent. Took me a couple of hours. I didn't get in any hurry. I cleaned around the dome windows on the camper plus the window itself with pure rubbing alcohol. I know I had some wax on the camper so I figured the alcohol would cut through the wax....I tried it on a small part of the camper to make sure it didn't do away with my paint. It didn't...just cleaned it really good.
I did the large dome window first....did the bottom first....then the two sides....then the top. I cut it longer than it needed to be and after over lapping the tape I trimmed the excess off.
This tape is really really sticky but you can pull it off if you need to replace it before you rub it in. After you rub the tape and get all the bubbles out of it, it would be a royal pain to get it off. After rubbing it with a roller, take the top film off and roll the actual tape again.
I bought an 18yd roll and had more than enough...I did the large dome window....the two small dome windows....the vent and on top across the entire back of the camper where there is a seam and looked like the sealant might be shrinking and I still have tape left.
Here are pics....I don't think it looks bad at all.