Thanks Shaun
In due course we might have to sit down together and see what can be done.

Lay the SP fav etc is vetoed. The lay for a return is the consensus.
Gruss can pick the possible SP ranking before the jump. I am assuming here that Gruss can also lay the field at different amounts to pay different dividends.
Lets look at a random race, (the last one) Doomben R5. Fine, 2000M, Good3, Group 3, 16 runners
Results 2,4,6 & 9
# BF$ SP WATAB $ $30 Liability $100 return. $120 return (outlay)
1 22 (23) 1.43 2100 2520
2 16.60 (9.10) 1.92 1560 1872
3 133 (99) 0.23 13200 15840
4 6.25 (5) 5.71 525 630
5 4.70 (4.40) 8.11 370 444
6 8.06 (7.10) 4.25 706 8472
7 16.6 (18.30) 1.92 1560 1872
8 107 (69.10) 0.28 10600 12720
9 20.9 (13.10) 1.51 1990 2380
10 7.60 (6.90) 3.95 660 792
11 48.6 (28.4) 0.63 4760 5712
12 23 (23.90) 1.36 2200 2640
13 35.2 (33.90) 0.85 3420 4104
14 120 (155) 0.25 11900 14280
15 66.1 (42.90) 0.46 6610 7932
16 117 (52.10) 0.26 11600 13920
32.86

Having got this far I can see that this was a poor choice to test on and I don’t think that I am on the right track, but shall continue because I learn and somebody else may as well.
Firstly I think that 16 runners may not be representative. The odds range may not be representative either. And I think the nature of the exercise was to win $100 no matter which horse won. This has essentially become a $16000 lay in the worst case scenario.

#4 won. The second fav. @$30 liability we would have lost $2.85.
@ win $100 as above then our outlay would have been $525. We would have picked up $100 on each of the other runners so we would be $1500- $525 = $975 – BF comm. $64 = $911 in front.
If the rank outsider got up then we would be out $13200, but would get $1500 back meaning that we would be $11700 out of pocket. In fact if any other than the top 4 won we would be out of pocket. If favs 5 or 6 got up it would be touch and go.
Thus it is not easy. However the 16th fav wins very few races. Going from memory it only happened once in my 43000 race database. The top 5 win >85% of the races. I can see a distinct advantage in staggering the payout. The stagger would have to be in accordance with the strike rate for each ranking. Unfortunately that strike rate varies mainly with the first favs odds and secondly the field size. Other factors only have a smaller range of variance. Thus we may have to be >$2 and 8+ runners.
I can see some heavy thinking must be done
Beton