Most likely this is a secret, but still Ill ask. Are there any setups for automatic dice to stay in a small minus, but wind up the volume for the competition? But most likely whoever uses this just will not tell me

there is no secret , you can use the most common strat - 98% winning chance
you can simply roll straight 10.000-100.000 satoshi and expect to lose around 1-2% of your bank eventually while wagering relatively high amounts
the problem is that you have to get a high initial bank and start early
or risk to get wiped when you get 2-3 consecutive reds in a row on a high base bet