R19 insulation ^^^ won't do much of anything for you, unless you stack rolls of it in the corners. Use OC703 or 705 or rockwool for acoustic trapping.
How does that open end of the room sound now? I can't imagine the room's natural reverberation will sound good there for recording acoustic guitar - probably sounds good to the ears when playing, but all those soundwaves bouncing around and picked up by the mic are going to be a mess on a recording. I'd set up a tracking area near where you have your desk now, use gobos (movable traps) to isolate the sound. The ceiling fan's position means you can't put a cloud trap over the mixing desk where you have it now, and trying to get any symmetry in the room for mixing is going to be near impossible. All you can do is keep adding traps until it seems balanced to you.