A 14.50% LOT using TAB prices.

Interestingly, where there were 9 outs 99% of the time a winner came in within the next 2 or 3 bets paying more than $3.00.

How about this as a starting point.

>$2.80 on the tote
Last start won or placed
Racing within 7 days

A 3% POT, stake that and you'd have a tidy profit, but not a lot of action.