If it's for one winter, use a tarp. Make sure you secure it well or the wind will remove it.
I wouldn't buy a cover for one season.
I use a cover on our Southwind and never had a problem with it rubbing or damaging the paint. We get a lot of winter wind in our area.
For the past two months I've had the roof covered with a tarp because of a leak. I plan on installing the cover and leaving the tarp in place for the winter.
I did this a few years ago when we got a lot of rain/ice/snow. There were no proasblems from the tarp under the cover.
But, a car port is a much better cover. Build it first thing in the spring, it's easier to use. :)