For Mirimir and other ~low anonymity personas, I just use a different VM and nested VPN chain for each persona.[0] If keeping them unlinked is not critical, I use the same host machine, and don't obfuscate writing style.
And because I use nested VPN chains, no individual VPN provider can correlate stuff from different personas. It's the same distribution of trust thing that Tor does. Albeit far weaker, because I'm only using several VPNs, and not thousands of Tor relays. But still, it'd take some effort to obtain logs from enough VPN providers.
If I care more about keeping personas unlinked, I make sure to use different VM OS, given the risk of WebGL fingerprinting. Because using the same virtual graphics driver and physical GPU gives the same fingerprint.
If I care even more, I use Whonix via nested VPN chains. With a different Whonix instance for each persona, or group of somewhat linked personas.
If I care lots more, I do all of that, using a different host machine, on a different LAN, with different nested VPN chains.
0) https://www.ivpn.net/privacy-guides/advanced-privacy-and-ano...