I actually think a "mega" vote makes it less likely self-voters would hide. When we consider attacks such as these we often ask ourselves what we would do to pull it off.
So, what would I do to pull off a self voting attack with linear rewards? I would make sock puppets that would post and vote on each other. I would post a lot so that I could spread out my stake without the posts ever getting paid enough to draw attention. I would never want to have large payouts but I would slowly siphon off the reward fund. Frankly, I wouldn't care how large someone's vote would be because I would probably not vote with full weight anyways.
If you have an attack that does rely on larger votes, I am eager to hear it!
RE: Proposing Steem Equality 0.19.0 as the Next Fork