I understand your rationale, but if history is a guide you'll need more than 3-4 years in cash if you want to "never have to sell [equities] in an extended down market." Even with dividends.
I'm using our actual investment history as a guide on this point.
I have complete records on our investments from 1982 through today. For more than three decades, we have had only three down years - 2001, 2002, and 2008.
Since we only had one occurance of back to back down years, we doubled that occurance and that's the reason why we have the 3-4 year stash in cash. It's not based upon "investment history" of the market, but rather our personal way of investing, and the results obtained.
BTW, we actually have more than that 3-4 years (actually 3 4 me, 4 for DW) since we have not accounted for my DW's pensions nor our respective SS income noted previously, which starts over the next two years.
Looking at our indivudial cashflow, assuming DW would have her pension/SS available today, she would have a decade of cash (yes, 10 years) of gross income available. So in her (and my) case, her actual long term can be stated that she currently has in excess of four years of gross income available.
We're not "harvesting" any more and directing to cash (something we both did, around five years before our respective retirements and as needed to maintain our cash levels during retirement), but just adjusting between equity/bond - rather than equity/bond/cash for the next few years until all our income sources come "on-line". And no, we don't use dividends for income. All distributions are reinvested into additional shares and sold/re-allocated based upon our own overall personal AA.
BTW, our actual cash held (as a percentage of our total joint portfolio value) is really not that high. It's not like we are exposing the vast majority of our "number" to possible inflation risk over the short term.
Anyway, it works for us; and really, that's all that matters IMHO...