Paul, This is what I've used on a couple cars I had to let sit outside before my shop was roofed.
https://www.ebay.com/itm/18-Layer-Ca...Cclp%3A2334524
They last bout 2-3 years in the south carolina sun/heat/humidity before the top layer starts to go. I had one on my firebird for about 2 years. I never noticed any paint damage, but it's not exactly a nicely painted car either.
As others have mentioned, they have loops to draw it tight under the middle of the car. This one also has an elastic band around the base like a bed sheet, so it wraps under the nose and tail pretty well.
We get some pretty violent weather here and the only time I ever had an issue was when I didn't tie the strap under the car.
If I remember right, you need your own strap. I used bungees.
They're fairly heavy and have a soft padding on the bottom. I would still probably test it out on your least favorite car first
