System partition on other drive?

I recently built a NAS (thanks to the help of the people here at myce forums) and am running into trouble. The whole UEFI boot thing is causing me problems, mostly in gub (file not found, something about invalid ELF magic, random black screen with blinking white line with no error indicator, etc). I can boot to usb just fine though, which is how I’ve been running my installation thus far. If I understand correctly, then I don’t have to worry about UEFI if the boot partition is < 2TB or something. Is it bad practive to just buy a physically small usb drive and boot off that?

Of course not.

I have my own FreeNas system working on an old 1Gb class 4 SD card (insterted in a very small usb adapter of course). It takes 10 minutes to boot its FreeBSD OS, but that’s ok. A correctly configured server will hardly ever reboot anyway.