only possible problem i see is that while you turn your key from OFF to START, your opus will see (very briefly) 12v from the lighter socket, but then as it actually gets to START it will lose power while the engine is cranking, then when you release the key and it goes back to RUN/ON, it will get power again. some PSUs don't like that and will give mixed results.
my solution was to have two relays switch power to the power-on trigger in my carputer. one relay was activated by the acc position (just like your lighter), and the second relay was active only while the engine was cranking (key in START position). yes, it made for another click inside the dashboard while starting, but it made my PC survive crank, and everything worked fine.
i don't have an opus - i was using an inverter, and was using my relays to directly cut or apply current to it. so i don't know what it's expecting to see on your trigger line, but i can't imagine that it's direct battery current. but like i said, i don't have an opus, so i could be wrong on that count. just something to consider. reason i brought this up is because when my pc would get that momentary pulse of power before my key got to START it would start to boot but then some devices (particularly the keyboard) wouldn't work. rather annoying!
Previous: CamryAmp 1.0 - 95 Camry SE V6 Coupe (sold)
Current: CamryAmp 2.0 - 98 Camry CE V6 5spd (still bench-testing)
Not all lighter ports are equal. Meaning the 97 Suburban my GF drives passes crank with my system hooked up with no trouble... my 95 Toyota does not, same set up with a different Automobile. Go figure.
D201GLY2, DC-DC power, 3.5 inch SATA
Yes, you should search... and Yes, It has been covered before!