Here I've taken VIX divided by SPX which shows the price of VIX in shares of SPX. When we do this we can see a channel which this relationship ranges. We can use this channel as a simple trigger to when to buy/sell vix into spx 3x ETFs.
In theory this trading practice will maximize your profits on SPX while protecting you from downside. Infact if the market tanks you'll 2x-3x your investment.