I've done a lot of acoustic guitar recording at home in, initially, an open untreated room - here's what helped me.
Buy a couple of moving blankets, get 3 mic stands, turn each boom so that it's at a 90 degree angle to the bottom part of the the stand - so in other words it looks like a t shape. Put the one in the middle exactly opposite the player and the other 2 angled inward slightly so you kind of have the top of a hexagon - now drape 2 moving blankets across the top of the 3 stands, you'll have to clip them in place to stop them from falling, I use large binder clips you can get at any office store, the kind you squeeze to open. So now you have a kind of a fake gobo, if the player is sitting down it should be tall enough. This will help eliminate a good bit of a bad sounding room and so will expand your mic placement possibilities.
Leave at least a foot between the moving blanket and the back of the mic. If the back of the mic is too close to the blankets, you'll get a weird muffled sound since the mic is picking up a certain amount from the rear as well. You'll have to experiment, this is way easier if you have someone playing and you're moving the mics around to hear what's happening. You can do this no problem on headphones if you have a pair you know and trust.
Once I started using the fake gobo method the sound of the acoustic recorded at home improved greatly - my problem had always been this awful dull, dark, lifeless low end woof and the blankets took care of that. I've also experimented with different coverings - I tried a velour blanket and a cotton blanket and you could definitely hear the difference, the moving blanket was the best.
In terms of your posted recording - I thought it was a tiny bit brittle and harsh in the mid range and if someone is playing hard, this is going to be a huge problem and a multiband compressor fix, so keep an eye on that. Thought the low end was fairly decent, not boomy or muddy.
As other people said, definitely record to 2 tracks, it gives you way more options. Something I try from time to time that I like is to use one mic to capture a bit more of the low end and and the other to capture a bit more of the top. That way, when you pan them in stereo you get almost the same kind of an idea as a piano, with the low end on the left and the high end on the right - BUT, they have to also share a lot of the same frequencies, they have to kind of meet in the middle so to speak, you don't want low end only on one mic and high end only on the other
As another poster said, definitely check your phase - put some kind of a plugin that has a phase flip on it, onto one of your channels so you can switch it in for a moment to check if your sound changes dramatically. If the mics are out of phase, the low end will sound louder and tighter when the phase is flipped on one of the channels, this means you need to move one of the mics. The ideal scenario is to keep moving your mics until it sounds right. The phase flip is just a check to see if stuff is positioned correctly - ideally it shouldn't be on the channel when you hit record. Again, you'll hear this clearly on a decent set of headphones
Don't be afraid to do a tiny bit of eq'ing as you record, I often end up having to dip down 280hz and 120 hz a hair but that could just be the room
Don't be afraid to go a good bit away from the guitar distance-wise, start from 6 inches and gradually move backwards and listen to what you get. In my room, the mic is typically somewhere around 10 inches away, depending on how hard the player is strumming. For easier, softer parts you can mic closer, with hard strumming you have got to move the mic back or it will be harsh, a little bit like on your posted clip. Typically I'll lift up the stand with the mic and just move it all over the guitar while listening on headphones to see what I get, this includes moving it closer and further as well. Once I've found the best spot, then I put the stand down and lock the mic in place
Your clip is decent though, you're not a million miles away, just a few little adjustments.
Edit: forgot one step I use - before I pick up the mic and start moving it around, I kneel down sideways beside the player with one ear next to the guitar, move your ear around and you'll quickly find a ballpark starting point for good mic placement. Listen for low end boominess, listen for harshness and brittleness and listen also to where there is nice airy, top end. That was the other thing I was missing in your clip, a bit of air and openness - maybe your mic is dead on the sound source? Try the 12th fret mic slightly higher than the neck and then angled down, so it's closer to the high strings than the lower strings - this should give you some air - oops, I mean lower and angled up, sorry, I'm an upside down left handed player!