G'day Mike,
All the best with your plan as any serious punters definitely need a "business" plan.
The only problem is that if a runner is showing $1.40 for the place this can shrink dramatically as the late money comes in. It is quite common knowledge that the bulk of money is invested in the last five minutes prior to race-start.
Also, could I recommend that you include in your plan to increase the unit value of your investments each time you win 100 units or similar.
Therefore you will have control over your betting bank and are not chasing losses which is the downfall of many punters.
Good luck to you.

Cheers.