Well, although I didn't go to the cabin, that meant I had a full weekend to cook. And since my brother and his family are in town and came over for dinner last night, I decided to go forward anyway.
I bought ~4# of beautiful marbled bone-in short ribs from Whole Foods. I seasoned them in salt & pepper, then put them as-is into the bath for 48 hours at 149 degrees. I figured there was enough fat that I wouldn't need to add any additional fat or sauce in the bag. After cooking, the meat had pulled back from the bone significantly, so I just sliced it away from the bone, and seared it in grapeseed oil. My wife made a simple red wine reduction (not using the bag juices), and we served it with a salad.
The result was perfection. The fat rendered, the collagen melted, and I had the most moist, tender, beefy short ribs I've ever eaten.
I will be doing this again.