So I would like to avoid a Pico for a machine which will be stressed out at times.
Well, I don't think all the Pico-esque PSUs are created equal, however, it's your call.
Nowadays among ATX PSUs there isn't about anything under 300W, and probably the quietest 300W available for your expected power draw should be the Silverstone SST-ST30SF
. It's a 80Bronze unit, SFX, so it comes in handy whith the smaller (SFF) enclosures (with an ATX plate adapter, in case of a traditional chassis), semi-fanless up to 55°C: check cable lenght compatibility with the case of choice. The second-best option (noise-wise) may be the Seasonic G-360, a standard (140mm) ATX PSU, quiet up to more than your expected power draw, very good electrical performances, and a couple of point more efficient than the Silverstone (for what it worths).
Whether you're going for an ATX-style case, the 4590T doesn't seem a mandatory pick, a standard 4590/4690 could be better suited, performance-wise, about as efficient and with about no issues cooling-wise.