Late to the party. That diagram is basically how I have been recording my acoustic lately. Except, the mattresses are walls, the room is a large walk-in closet, and behind me are layers of comforters and blankets. Behind the mic is a reflection shield, above it is a pillow resting on the shield (to stop sounds from coming into the mic from above), and...that's about it. I point the mic at about the 14th fret. I sit when I play, and the mic is straight up, hand height.
I don't know much about recording live stuff, and these guys here and experts. I'm just sharing what I've done since you referenced me a couple times. I think my sounds could be much better, but I'm working on that. There is a bit of EQ on the guitar bus as well, and don't forget that you're hearing double tracked guitars, panned about 25% (hard pan doesn't seem right for acoustic). The EQ is removing low end resonances and muffled/boomy sounds. No LPF. A couple high end notches in the 2-7khz range, where the pick is making noise and there's a scratchy sound.