It's good to remember it's being proposed as a purely optional system.
Speaking of which, let's talk about the exact prize/ranking/bonus implementation.
I'm thinking something like there's a second "track" of Highlander winners, 1st, 2nd, 3rd, probably a significantly smaller prize. Then if those winners overlap with the actual winner, so be it, it's a bonus. Whatever the value, I think it should probably be just enough that a 2nd place winner that was highlander would get more than a 1st place winner that was not.
Or you know, maybe all the highlanders are all at the bottom, but at least they got something for their trouble.