I didn't exercise for most of last week. My back was still bothering me, so I decided to back off and see if I could get it cleared up. The good news is that it now feels about 95% OK; I just have a few sensations at times. I did end up riding (easy) a couple times, and I played hockey Sunday night. So, I didn't totally just sit around.
I also continued to practice my bike handling skills. I feel like I made a little breakthrough with my manuals this week. I'm still not getting back far enough to hold the front wheel up, but I'm definitely getting close. I am getting back far enough that when the front wheel comes down, it lands pretty softly.
I want to get my manuals really dialed in, and then move on to a proper bunnyhop / J-hop. The video linked to here is, by far, the best J-hop video I've seen. I think, maybe because the jump is so big, the different parts of the technique are exaggerated and pretty easy to pick out.