Just going on your results data alone, I can see some serious problems with your system.

Firstly, a win strike rate of 43% never has, and never will, produce a *permanent* POT of 21%. You can get that type of POT over 100 or 500 or 1000 etc races BUT, and this is immensely important to understand, the figures MUST eventually even out...... during this evening out process which is inevitable, you must be in loss, not profit.
A 43% strike rate (which IS definitely permanently achieveable) will normally produce a marginal loss over the very long term, regardless of staking methods used. A very smart professional, who's on the ball and extremely diligent may, just may, scratch out a 1% or 2 % POT on a *permanent* basis from a strike rate of 43%.

There's another serious problem with your results..... it's the high place strike rate. A *genuine and permanent* 43% win strike rate should be accompanied by a lower place strike rate than your 82%. If it's not then it shows there is fault with the win selection method used. So, *Long term* that 43% win strike rate will most likely come down by several percent........ and that will guarantee a long term loss of several percent on turnover.

Wish I could bring better news..... but those are the facts.