RMD – IRA strategy

I have 2 IRAs with comparable balances.
One is a Fidelity Balanced Fund (60% stocks / 40% bonds & cash).
2nd is a Vanguard VTWNX TR 2020 fund (30% stocks / 70% bonds & cash). Now virtually same as VTINX Vanguard Retirement Income Fund.
My rationale is that I have flexibility to withdraw for RMDs from one or both each year, no matter the stock market performance. For example, withdraw most or all of RMD from VTWNX conservative Vanguard fund in a down market year. I also move 1+ years RMD $ to each IRA’s MMA cash position the prior year for chicken money in case of a significant market downturn. Is this a valid strategy. Any downsides? Thank you, Terry