Bike cover to recommend ?

[Fontinalis]

I will be driving from the East coast to the West coast, and back, this summer, with my brand new bike on the bike rack (the kind that hooks in the hitch of the car). I have been advised to put a bike cover because debris from the road would just ruin the bike (chip the paint, dust in the gears, etc.). I have shopped high and low for this. I find either cheapees that will tear at anything. Or huge bulky ones that will prevent the car behind me from seeing my braking lights when they come on (my bike is just a few inches wider then the back of the car). I'm just about to go buy some plastified textile and do it myself! I saw one bike cover where, ingeniously, the lower exterior corners of the bike cover were transparent (adressing the brake light issue), but it was made of such a cheap plastic film, it would probably last just a few handling. Any covers that people have used extensively and would recommend for this particular use, when their bike is on a car rack ? Mine is a Swagman, the kind where the bike just sits on its wheels in oval brackets, and there is a hook that holds the top bar, so no need for holes to go through the bike cover). Not sure if this is the right place in the forum or if I should have posted this in 'gears'. Sorry if I'm in the wrong area.