The idea of keep "extending" the loss is ugly. Why don't you try the stop-win feature on the auto mode? I found this helpful for martingale strategy. The problem with martingale is greed! It "forces" you to play longer than you should and eventually lose everything.
That greed place your position always to be in the negative side, whatever system you tried if your attitude towards this activities are being occupied by emotions then there's no way that you can win over the house, martingale will work alone only if you can control your emotions and you can quit much earlier to avoid greed to control your stay.