My car is garage kept except for vacations when it rides a trailer. What car covers can stand up to the slip stream and not scuff the car's paint?

 

The short answer is none. All covers will be buffeted and eventually abrade the cars surface areas. I would see if you can rent an enclosed trailer in your area, or simply use painters tape to cover the front/including the windshield. Even a product like Road Wrap makes a good temporary protection that's removable, save the cover for when your parked.