This might be dumb but would immediately payable bonuses/negative fees incentivise more trading than just offering to buy above the peg?
Idea
Participants can only buy BitUSD at exactly 1-1
Participants can only sell/short BitUSD at exactly 1-1.
No forced settlement (Or much lower like 0.95)
Participants compete on the negative fee they are willing to offer the other side & the order book is ranked accordingly.
Example
I want to buy BitUSD but there are no sellers at 1-1
There is already $1000 of BitUSD buy orders with zero bonus at 1-1
I offer to buy $100 of BitUSD with a 1% bonus.
My order goes to the top of the order book and would be filled first.
Whoever sold/Shorted BitUSD to me would receive a 1% immediate bonus/negative fee.
Subsidising liquidity
If BitShares wants to subsidize liquidity they can add to the existing bonuses/negative fees offered by market participants.
Example
BTS could offer 0.3% a day on $33 000 worth of BitUSD, ($100 daily cost) This would mean if you sold or shorted USD at 1-1 you would receive the bonus offered by the BitUSD buyer and an additional 0.3%.