re: Thoughts on 401k and possible recession

Unless you're planning to retire soon, why be worried about a recession. As someone pointed out, it's just paper losses until you actually sell. With 25+ years to retirement you should welcome recessions, crashes etc. Lets you buy more with your money.

I don't think I've ever seen anyone who understands modern portfolio theory recommend staying out of the US stock market all together. Unless you already have several million and not concerned with long term growth.

The "permanent portfolio" is something that comes to mind when I was reading this. https://www.bogleheads.org/blog/harry-brownes-permanent-portfolio/

I'd be pretty confident the below would beat out what you propose over the next 25 years with less volatility
50% Total US Stock Market
50% Total US Bond Market

Take a look at this. I think it will help.
https://awealthofcommonsense.com/2014/02/worlds-worst-market-timer/

Unless you plan to change your investing strategy, market time, etc whenever you think you know better than everyone else. Good luck with that..