Another choice I've been thinking about is you could do a "Poor Man's Covered Put." Buy a deep ITM put in a back month, and sell OTM puts in the front month. It still doesn't look too feasible that far out to Dec, but I'm considering doing one maybe for June/July or June/Aug, e.g.: Buy SPY July 255, sell SPY June 233 puts. Costs around $16 today. Max profit = 255-233 = 22 - $16 = $6. Max loss $16 (if SPY rallies past 255). Gives you around -45 deltas of downside hedge.
I don't love calendars; I've had mixed results. I find them fairly slow to profit, but not very risky either. Just trying to offer some ideas.