I haven't seen a bond tent that drops from 85% to 50% equities in one year, nor one that starts 2-4 years before retirement. There's some interesting research on bond tents that might be a more comfortable approach than what you're considering.
When I've looked at PUT options to protect against index losses, the downsides have kept me from buying. On the $388 SPY (S&P 500), you can buy PUTs at $310, $350, or $388.. but it costs 3%, 6%, or 9% of the stock price for 1 year. Stocks mostly go up, so PUTs mostly lose value - and expire worthless, if held that long.
If you do have a loss, and the PUT has value... when do you use it? It's a market timing decision, deciding when the bottom has hit. Use it early, and it does nothing against a following drop. Use it too late, and you paid for protection you didn't use in time.