The ratchet strap might have been a bad idea (I just said it's what I would do, not that you should! (and I realize you didn't))
For future, and from those with experience, would you have suggested draining at least half the tank first and then moving the rock? I'm guessing the water movement from lifting rocks finished the job.
To Matt, good luck! I have a 55 and 5.5 gal and some bins sitting empty if you can't find anything closer than Cumberland. You probably have a plan, but figured I'd offer.
Edit: too slow on my part, but thank goodness for you!