Gamma scalping? What're you like independently wealthy? How are you picking equities for these bull call spreads?
Seriously if you want to take very low risk and hence very low reward, don't trade. Better put money in the bank, or go buy some insurance like endowment policy. If your frame of mind is not appropriate, very difficult to profit from trading. Opportunity from trading is very huge. So frame of mind should be to earn tons of money, not meagre profit from trading.
I sell strangles, theoretically an extremely risky strategy, so I have no such problem with risk; the low risk/reward I am looking for is confined in the context of a larger strategy, as explained in the post.
This is the most common financial question I'm asked by friends/acquaintances: how do I try to make a little conservative money without taking a chance on losing any of it? Unfortunately, the answer is to buy a mattress.
Consider a momentum-based Index strategy using the ADX or MACD on 1-day candles {w/ end-of-day triggers}. While often maligned , it's a nearly-trivial effort to develop a positive expectancy, with risk much less than market. Positive trades ~ 7 days; negative trades ~3 days. Play with the parameters til the behavior matches the market you're working. Set; forget. Positive trades ~ 7 days; negative trades ~3 days. If you really want to work your strangle markets, test a tailored momentum indicator in that market, and put some $$$ on it.
You're either going to park your money in Treasuries for what, like 2.3% for a 1-year now?, or you're going to take risk. IF you're going to take risk then stay away from super high winning pct systems. This market is going to easily get cut AT LEAST in half from wherever the last high tick of the S&P 500 winds up this go-around. You'll have a 3-6 month window of 60-80 VIX readings to plan your 3x+ bagger plays over the ensuing 5 year horizon from that. But forget about low-risk / low reward / high winning pct systems. You're far better off in fixed income investing then.
As already suggested could you park your money in Treasuries. Alternatively could you park it in a basket of ETFs. Select some that have a somewhat positive expectancy coupled with low risk for the expected duration of the investment, and use these.
CXO Advisory has just published 20-year results for the SPY:SMA10 strategy (refers to 10-month MA). Compound return 10.1%, SD 10.2, rough Sharpe 0.99, worst drawdown -18%, worst annual return -4.2% (in 2015). No, I can't post it; you have to pay for their site; but you can easily figure this out for yourself. Maybe it's not as consistent as you want. You can try it with a less volatile ETF.