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Take this advice with a grain of salt since I have never played BJ tournaments.

I would not use martingale. Since it usually results in either a small win or a large loss. I'd use some sort of reverse martingale where you press your bets as you win. Or you could always bet half of your bankroll until you either bust or take a commanding lead at which point you can min bet for a while until you need to make up some more ground. This definitely looks like a decent EV opportunity so maybe you should look into some sort of casino tourney book.