you must think outside the box my friend. get rid of the birds. and i don't mean shoot them all. get a system that will make the birds leave, one of those ultrasonic noise machines that sits up and makes noises that bug the crap out of them. either that or get a big birdhouse ELSEWHERE and lure them there. all of the things your listing as ways to fix this are going to end up being a pain in the ass. don't inconvenience yourself with annoying car covers. i have always parked in my garage but this summer had to park outside because of construction on my house. to get rid of the annoying birds and other creatures i trimmed the trees back from over the driveway and parked as far away. i also set up a bird feeder elsewhere in my yard. it worked. noproblems!