I'm not going to speak in hypotheticals and theoreticals here, but I'll speak from practical experience with what I've actually done. I have a 60 gallon 3.7 hp 13 CFM compressor now, but before that I had a Crapsman 5 impossible HP from 110V 20 gallon. I ran a whip from it to a water filter/regulator on my wall, and that's where my main line tied in. I could easily spray an engine bay with my 20 gallon. In fact, when I moved out here to Michigan, before I got the 220 ran in my shop for my big compressor, I was spraying with my little 20 gallon and it does just fine for small things like an engine bay. I know yours has 5 gallon less capacity, but take this for what you will.
Something else to chew on. I took my engine bay down to bare metal, primed with Sikkens 1K wash primer (etching primer in a rattle can) and sprayed two coats of Bill Hirsch chassis black (also in a can). The cans have the tip that sprays the pattern so it lays on nice. This I did in 2009. It looked great then. And still looks as good today as it did then. There's only one part of my car that I haven't had to continually sand down and respray because of rust popping through throughout the course of my restoration, and it's been the engine bay.