I've run my 21'x12' tarp over my CT no probs and have left it there for up to 2 weeks. I have never had an issue with condensation build up and found it much cooler, and of course dryer. Although, I have recently been placing a couple of poles at either end (or tieing to a tree) to lift it of the CT canvas and it has made a difference temperature wise letting air circulate under it, similar to a capricorn top. I have just tied off in the center down onto the trailer, or peg it. This, of course is only done when I plan on staying for a period of time. I haven't found any evidence of rubbing and wearing yet (fingers crossed). Basically I just set my camper up as usual and last thing drag the tarp over the top, starting from the back and working to the front. 1 person either side and lifting it over like a large sheet. I tie a length of rope to each corner of the tarp that is being dragged.
Life can throw nothing at you that beer won't fix