The short answer is, there is no way to completely protect yourself against Black Swan events other than to give up trading. There is an inherent risk you can lose every penny in your account if the worst happens.
The reason I stick with 1% per trade is exactly for this reason. If we take the extreme example of the CHF un-peg from the Eur in January 2105, that's about as extreme as it is ever likely to get. I've certainly never seen anything like that in the past. So let'stake that as a worst case scenario. In that event, if you were open with a position size on the smaller end of your typical value, like you sad, you would have lost around 75% of your account. If you had a greater number of lots open, you would have lost your entire account and perhaps owed some.
There are really 3 options when you are trading a larger account:
1. Accept the risk and make sure if your entire account is lost, it is not the end of everything for you. It comes back to the axiom - only use genuine risk money. One of the ways to ensure in the event of losing more than is in your account and you owing money to your broker, that you are not personally liable and end up bankrupt, is to trade via a limited liability company. If the company goes bankrupt, at least it isn't you.
2. Trade even smaller risk per trade of perhaps 0.5% or even less.
3. Trade with a higher time frame perspective. So instead of trading 5 minute charts like I do, adapt the system to trade with a longer term perspective. Remember your position size is related to your stop loss size in pips. Smaller stop loss means bigger position size. So your typical SL on 5 minute charts may be 30 pips; on daily charts it could be 250 pips. In this case each trade is still only 1% but your position size will be tiny compared to what you are used to.
The issue with option 2 and 3 is the diminished returns. If you risk less per trade, you make less in return. If you trade longer time frames, you get fewer opportunities (you may only take 40 trades in a year as opposed to each month). It depends on what is more important to you and what your comfort is. Would you prefer to make 10% per year with virtually no risk (option 2 and 3) or are you happy to take greater risk in the goal of making bigger returns.
Just like individual trades, your whole trading strategy is a trade off, more risk more return or lower risk and lower return. There is unfortunately no perfect middle ground.