Something similar to the following seems promising. Picking the correct strikes and DTE as well as exiting in a timely fashion is needed. This is addressed by TheoTrade.
BTW: I have no personal experience with this, but have similar interest. This looks easier than it probably is as noted by Martinghoul above. Below is a plot of this position, as well as an alternative moved down to only address > 20% drop per your original post. Take this with a grain of salt (and a shot of Tequila), as there seems to be a Bear behind every tree and a snake under every rock in this business.
See a backtested history of VXX to see why buying puts for protection is a bad idea. Ignore that crap about Taleb and blackswans. Puts are waaay overpriced...many academic papers have been written on the matter and all conclude puts are overpriced relative to the risk of a crash. If you are bearish, there are better strategies than wasting money on overpriced put protection: buy treasury bonds sell some stock sell a call option move to a low-volatility fund or a consumer staples fund sell out of money puts instead of being long euaities
Along the same lines I was wondering if there is a tool / website where you can in effect input your portfolio and then look to calculate the best way to offset using puts. Obviously I could just buy puts in the S&P but my portfolio is overweight tech, financials so I am sure I need to get a better hedge than straight S&P.
I suggest you apply a Dalio 'risk parity' type approach. You give up a few % returns every year in order to protect yourself against the bigger drawdowns that happen in equity indexes. Paying for puts and other things like that, I'm not sure that is a good idea at all. at least for most people
Cool. This is exactly the kind of hedging I was looking for (and nice piece of software btw). Implementing it the right away is obviously more complicated, but it's a good start.