Hi
You might try using a banker with your dutching. Here is an example of 4 horses covered by dutching. The first group is standard dutching for a $50 bet.
Price Units Profit
$3.60 18 14.80
$5.00 12 15.00
$6.10 11 17.10
$8.20 8 15.60
Total bet 50

This second group using the same prices has made the $3.60 horse a banker. That is it is calculated for just enough return to cover your bet, but look how the profit on the other horses has gone up by approx 65%.
Price Units Profit
$3.60 14 0.40 (banker)
$5.00 15 25.00
$6.10 12 23.20
$8.20 9 23.80
Total bet 50

You would probably use this type of bet when you want to hedge your bets by covering the favourite in case it came in.