Boosting longer-running algorithms is definitely something that we've thought about. I never found a formulation I liked. The cure always ended up being worse than the disease. I haven't found a solution that does as you suggest.
I know this is a old post but I'm unsure if this problem has been solved (IMHO it hasn't as the backtests are only 2 years).
One of the most important questions is what are you actually trying to get with "score" that you are looking for. Long term survival? Minimum risk? Short term volatility adjusted profit in current trend environment? I would assume longer term survival and vol adjusted returns?
My humble opinion: If your contest lasts only a month and backtest only 2 years then it is not just hard but impossible to find a scoring method that works. If you have lots of competitors in the competition then there is no way to escape survivorship bias especially if the last 2+ years are similar or quite similar market regimens (the case at the moment).
I have been developing genetic trading algos in the past (and these little things really want to cheat if they can! Few of them exploited a bug in the framework that I was using to win for example..) and the most reliable method was really long backtest that was consistent. I know backtests don't tell that much as they can be curve-fitted but at least they tell you something if you have 10+ (preferably 20+) year performance that is consistent in different market regimens.
On longer term tests one simple fitness score was best of all the others I tested and most consistent in out-sample - it was "MAR", ie. annualized profits/max DD - almost the same as "calmar ratio" that you were using at some point but with scores calculated for the whole period.
At least I would consider making backtest for the competition last a few market regimens and quite a bit longer term (10+ years), otherwise you are into nasty surprises with real assets and algos that "win" in current regimen but will be killed in downtrend. I could probably make a algo that would be very consistent in last 2 years + month but there is really no point in just aiming to win one competition when the actual target is long term survival.
Just my 2 cents.
(edit: It seems contest is not 1 month, it's 6. That's better but still not survivorship-bias free)