A simplistic approach I ran through the now defunct Online System Builder, I came up with this.

RULES
Must be top ranked in place percentage.

Must have run exactly 4th last start.

For whatever reason , it showed a good profit for Sat Metro racing tested over 2 tears of stats.

I am not sure how it would perform on other days or non-metro tracks,.

Maybe Chrome could give it a little run on his excellent data base.

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Cheers.