Regarding your S&P Volatility analysis i like the idea to use it as a psychological support in times of uncertainty, but i guess i would never use S&P related indicators for BTC trading.
The reason is simple, S&P cycles are much longer than BTC cycles and i would not mix them.

Regarding BTC we had some full cycles since 2010 and a lot of data Points relating to all cycle phases.
Regarding S&P we only have one big bull market since 2010 only interupted by some "minor" corrections.

In simple words: continuously printing money as hell (low vola) is good for S&P and BTC. Major global crises resulting in corrections (high vola) is bad for S&P and BTC. Thats my stronly shortened interpretation of causality behind those correlations presented. That could be completly different in an S&P bear market.
Despite that i guess low S&P vola can be interpreted as low risk of fundamental changes in world order. I guess therefore it is still a good "soft" indicator to confirm the gut feeling. 
I also guess there are some opportunities to use this as an indicator across the board, e.g. for rebalancing diffent assets.

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Regarding your DCA Analysis i would partly agree. Within a strong bullish trend overlaid by cyclical fluctuations it seems logical to me that a simple savings plan is mostly weeker compared to lump sum investment. BUT: I don't think that is the question!

The question for me is: Can we improve the cycle based entry points by using DCA as a money management tool (not as an indicator)?
Using time based DCA: Is it better to buy @ Trend price -40% / ln(-0.5) all at once or starting the saving plan for X month from than.
Using price based DCA: Is it better to buy @ Trend price -40% / ln(-0.5) all at once or split basket to buy @ -0.5, -0.6, -0.7, -0.8, -0.9 and -1.0 (and eventually miss the dip with some orders an have some FIAT left)?