After blowing so quickly through legs, that left 15 minutes to do abs. Incline crunches to start. The first set of 20 almost felt easy. By the third set, I couldn't even do 5, and my belly and flanks were plotting rank mutiny. Finished abs with "prone isolinear abs" aka "The Plank", which finished the wipe-me-out process.
I hobbled out of the gym, but was mostly fine within half an hour.
If my knee continues to hold up so well (it only got a little bit more warm than the other only during the heaviest loads, I suspect that the Free Squat will soon be back on my roster.