Hi C.E.

Your method has the basis of being "doable" but I respectfully offer the following considerations and thoughts:

Perhaps only bet on Metro events?

The "within 4 lengths" theory is one of the most over rated around. You are better off considering a horse that finished in the first 4 last start regardless of lengths from the winner.

Ruling out apprentices means missing a lot of good value bets.

Barrier positions are not overly important in the overall scheme of race results. People will point out that numbers 1 - 5 have the highest strike rate but there are always horses in barriers 1 - 5. There are not always horses in barrier 10+ because field sizes determine this stat.

If you want to bet 50 units, try 15 x 35 maybe. Even 20 x 30.

Have a look at runners listed in the newspaper market between and including $3.50 & $11.00.

Have a play around with your method and try and refine it here and there.

Good luck

Privateer