We had a vice once, though we never got to use it, unfortunately. It was one of those that has the wood (or whatever) that sits on the top and bottom of the breasts and is tightened. Master bought it when I first got back up to Canada in hopes that I could return to Texas, but it wasn't so. We still have it, though it is locked in a storage shed 2000 miles from here with all the rest of our stuff, along with our spreader bar and paddle that a friend made for us.
I have never had clover clamps (nor alligator for that matter) used but both just look a little too nasty for my liking. As for the harness, well maybe my dear Master over there would be willing to descrive it a bit better. It's too bad we don't have an pictures of it, though I guess it is easy enough to make.