OK, I think I get it now (man I hope I do)...
So, the requirements are:
- you want only 1 bounty
- you want the bounty to be $10 X the number of players
- you want the stats to accumulate bounties won, bounty money won, etc
The first two items can be accomplished by using a bounty prize. But a prize designated as a bounty isn't counted in the various "Bounty ..." stats. It is simply another prize that is awarded in a specific way. So you can't use a prize.
The second and third can be accomplished by using bounty chips. But the first point is tricky, since anyone buying bounty chips (which would be "contributing to the bounty prize", as it were), will have a bounty on them, which cancels the first requirement. You've found a clever way around this, by designating all the buy-in from one player for the bounty chip, and no one else buying a bounty chip, and not restricting bounties to those who bought bounty chips. But it only works because your buy-in happens to be exactly the bounty amount due to the number of players.
The problem occurs when you increase the number of players. This increases the bounty amount, but not the buy-in (which happens to be the same).
Unfortunately I don't think there's anything that can be done that will satisfy all 3 requirements. You cannot adjust anyone's bounty chip amount like you can adjust a player's winnings, points, etc. So the only way to increase that bounty chip amount/winnings is through the bounty player's buy-in, which will throw off the bounty player's Total Cost, Total Buy-in Amount, etc (which you've already noted). And if you use a prize, you won't get the stats.
Sorry, I can't think of anything beyond what you've already done.