First, as noted above, if you are taking out only 3% a year, you are in all likelihood going to be just fine, even when the market crashes for some period of time.
If you start with $600K and will need only about $5K of that per year, you could put it all under your mattress and still have enough to cover 100 years; even if you draw 3% of that per year (18 years), that will cover you until you're almost 90 -- even if you never earn another cent on that money. Put it all in CDs and you can probably live off the interest and never even touch the capital.
But financial success is emotional as much as it is math. The last thing you want is to be too aggressive in your investments and then panic and sell when the shit hits the fan. And really, where's the fun in retiring only to fret over your finances all the time?
IOW, you don't actually need to have so much money in the stock market to cover your needs and then some. So if having so much in VTSAX is making you fret, move some of that over to something like CDs.
One strategy people use to manage down markets (without using your mattress) is to keep anywhere from 2-7 years' expenses in a CD ladder. If you're 7 years out, you can start that now. This year, pull that 3% that you want out of VTSAX and buy CDs with it that will mature in 7 years. Next year, pull another 3% out and buy more CDs that will mature in 7 years. Do that every year. By the time you retire, you will have the next 7 years' expenses (plus interest) becoming available right when you need them. Then keep doing that. Except if the market crashes, take a break for a year or two. You have enough "safe" money to ride out even a long crash. Then, when the market recovers, you can replenish the ladder to fill in those missing years.
The value in the CD ladder isn't so much about maximizing earnings -- it's about giving you the confidence to ride out any market crashes without having to worry about them. So if the math alone isn't enough to make you feel safe, strategies like this can help calm those fears and allow you to just enjoy yourself without unnecessarily worrying so much about your money.