just my little experience: is an overkill.
An adapter of this kind
is cheap, reliable for the purpose, and easy to find pretty anywhere; plus a SATA small SSD that you can buy used or new (on aliexpress the 60-120gb are really really cheap).
Use the joe’s multireport script and you don’t neither need to mirror the boot pool, if in case of something goe’s wrong you can wait the 15-20 min that a clean install+config upload needs
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