Quick update: I sanded off the slurry; I started off with the block-and-sander and quickly went back to the random orbital; hand sanding is just way too time-intensive and I'm not all that picky. Orbital down to 220, then hand-sanded @ 400 and 600, swapping out the paper a few times to keep it fresh. The TruOil instructions say to stop there, so I did, even though I have 1200 and 1600 grit or whatever. Then another good rubbing with a tack cloth (actually a good tack cloth rub-down between each grit).
Then, again, I added some TruOil, this time a very conservative coat, just like the instructions say. It dries much more quickly with this super-thin coating, so it helps to work it for a while to avoid streaks and such.
The filling strategy worked really well; it's still going to be an open-pore look, but in a very subtle, natural-looking way... as opposed to the more "varnish peeling off" look on the back of the body. I'll take some photos after the next coat dries, it looks a whole lot better than the back. This has been a lot of fun.