The double-nut system works well. Yes, with the nuts both in place and the outer flush with the end of the stud, a good whack with a hammer will help to loosen things up.......especially if they have been sitting a long time.
The clamp-collars come in pairs.......2-left & 2-right. If you want them somewhat ruff but intact, I have a few at $5 each plus shipping but no bolts. I would have to check to see if I have correct pairs. New units are $25 each or more plus bolts. Check with your local dealer.