AIM as normal, inflation adjusted stock index price, but where if AIM-CASH transitions negative, set it to zero. So it moves back into some cash at the first sell trade, rather than potentially being stuck down in deep-down, all-cash-deployed limbo.
Identify ongoing AIM-CASH value / portfolio value, as normal, but cap it to 33.3% if less than 33.3%, 66.6% if greater than 66%, and sandwich that between stock and gold. So thirds each stock, AIM, gold (silver pre 1975 (gold prohibited), T-Bills pre 1933 (non-fiat currency era)).
Extract out that central AIM third and its growth rate slow beat all-stock, and its SWR was significantly higher than all stock, 5% instead of 3.5%. Heavy fuel.
If/when AIM is down into deep down territory the outer layers (stock and gold) keep things working (67 stock/gold rebalancing).
A factor with heavy fuel alone is that you have to be prepared to be all-in at times. With the sandwich you range between thirds stock/gold/cash at market highs, 67/33 stock/gold at market lows, broadly average 60/40. Which is less stressful for some. SWR is still good either way, comparable, yes fuel heavy will tend to average more rewards, but not that much more on average, 9.5% versus 9.1% growth rate slope differences.