Buy an investment property (though, good luck finding a good one). Owning real estate, especially leveraged real estate, is a way to diversify. So you are giving up diversity and then asking how to diversify. I know you said no to RE, but unless you want to take on a lot more risk, it's the other option.
You cold also invest in a business, though that's fairly high risk and with only about $385k in investments it would likely take up a very large portion of your portfolio.
Microloans? Or just mini-loans? I'm not sure if Lending Club is even still doing them, but if not you might be able to find someone else. Inherently risky, especially if you can't find a platform for diversifying with many small loans, but if you just want a Thing That isn't Equities, Bonds, or RE, it's an option.