On that point (needing a sys admin for say 10 hours a week), where should a currently devs only team be looking?
Remote freelancer? Dev with ops / sys admin experience?
If you've already got something in place and operating at <10 hours a week, I'd keep it in house with whatever dev has more ops experience. Or whichever one drew the short straw after no one admits to having ops experience. You could hand it off to your newer hires to gain an understanding of what you do. The key is to define who responds to what.
Keep an engineer on retainer that you can call in to handle one-off builds and emergencies. Big changes/deployments where you can't afford to gain experience the hard way.