How do you allocate a portolfio with the primary goal of long-term growth... but, with a chance that you may need to tap into a portion of it early?

So I think we're all agreed in that for long-term growth it's better to be all-in on stock index funds. And while I would love to say that, I also know that there's nonzero chance I'll need to tap into a portion of my after-tax investments earlier than I anticipate. This would most likely be because of a job loss - which could likely be correlated with a downturn in the stock market - so I'd be liquidating my investments at the worst possible time.

With this in mind, I'm wondering what allocation would make sense for me. Should I be investing a portion of my portfolio into bonds? My main concern there is how unfavorable the taxes would be for me - my marginal rate is 35% + ~2% NIIT (so 37%). That alone really seems as though it could eat into my long term growth. I'm okay taking a little bit of risk here - I'd rather not have 6-9 months of expenses sitting in an emergency fund for an event which may never come. (I do have an emergency fund, but I keep it at 2-3 months)