My vote is for no cover as well.

Road salt, grime, etc. is food for the bike! Besides, a water hose will rinse that stuff off but trying to remove the scuffs, fabric burns, scratches, etc. associated with a flapping tarp will involve a lot of time, frustration and $$$. Heck, flaunt that Valkyrie! Remember this...most folks have never seen a Honda Valkyrie, much less seen one in the bed of a truck

I had to haul mine home in the bed of a truck because of a hurricane blocking my path last year. Most folks were in awe of the bike and especially surprised to learn it was a Honda.
Jim