After many hours of fiddling in Unreal Engine, I've managed to get a high-res still image with acceptable lighting out of it! Certainly far from perfect, but we have soft-ish lights, depth of field, I even managed to try out camera and light tracking. It's an extremely ungrateful process, highly unintuitive and seriously not user friendly. Tracking a light in the editor requires you to write 4 separate classes in Blueprint for example, it's certainly not a one-click affair.
I've posted some more background info, together with links to articles I've written to make this happen: https://www.patreon.com/posts/61462937
The character was a freebie a while back called GR Female, and my test project was called 427a (hence the highly creative title).