Tails maintain convexity from 0-inf. Small haircut ($3K debit). Crazy rho on long-dated but that is simply opportunity cost (moot) and this is a 2W combo. Allows you to trade short-gamma locally with no bear-risk.
Beat tail is conservative due to vol-corr and upside due to stickiness, but I typically model a touch of the the bear trough to x as vol-corr (- to index) will shift the curve higher.
It's an ideal portfolio prot. I arb VX against it (long switch say Dec/Jan for convergence gains as SPX/cash convexity exceeds leverage to VX). IOW, you can arb the long switch in VX against VIX SOQ.
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Regarding VX... You can see the leverage to a 3% move downside which would result in perhaps a touch of 20 VX in the Dec. Arbing VX against isn't cheap but you can trade outright short VX against in lieu of the switch -> say, long Dec/Jan; Dec/Jan/Feb fly, etc. I can sell 10x outright in VX against this structure w/o risk.