Thanks for the responses. I did manage to beat the game around midnight on Sunday after failing so many times I lost count (maybe 30-40), though I'm not sure what finally put me over the top. I'll recap what happened.
@AweOfShe: I cycled through a couple of the amulets and spent most of my tries hammering the Dance button (my highest stat by far) until the Visual multiplier was maxed, then hammering Visual until Vocal was maxed, then bursting with Chihaya, using combo memory appeals to get to max voltage. But the points were always short- I got no closer than 3k points. Then again, I used Dance image songs almost exclusively- does the song type get added to the burst?
@Lyssa: I left the burst bar charged at max a few times, without hitting R1, but it always got knocked down anyway by a counter burst. Was I supposed to stop hitting the regular appeal buttons too, or is there a way to prevent counter bursts?
The setup I succeeded with: high stats after Hell Training, 5 memory appeals, Nashida-san amulet, Go My Way, and bursting twice with Chihaya (to Jupiter's one). I couldn't prevent Jupiter from bursting and their voltage rose much faster than mine, so I had to tinker with the timing of the appeals/memory appeals to get the meter to max without provoking Jupiter, burst, let Jupiter waste their appeals to burst, use my remaining appeals, then scramble to finish charging the bar before the end of the song. I failed repeatedly because I would almost max the bar, then a counterappeal would knock it down right before I could hit R1 (mashing R1 did not help). I probably used a 3/2 before/after memory appeal split, comboing them of course. I needed the third appeal just to recover from their counterappeals.
The multiplier decay with the amulets I had was awful, so I had trouble charging the meter. I wound up using the 1.10 multiplier reset from the memory appeal to squeeze some extra points from my exhausted multipliers before bursting. Since the buttons you hit during a burst are random/spread out, charging up a 1.50 vocal multiplier did not seem to help. I hit the burst button as soon as I was able.
Final margin of victory: 500 points out of a 30k/30k split. Two appeals to one. If I'd whiffed on fewer appeals, I might've won sooner, but that was my best effort. I took a screenie to remember this one by. I used a similar timing strategy to finish the extra RK episode, though it only took a few retries because the power gap is smaller.
In my opinion, this game's Normal mode has two difficulty tiers- FAQing with the best amulets, and doing without. It was a mistake to think I could win with my puny skills- it's powergaming for me from here on out. I want to unlock some good costumes, so I'd like to put Yayoi and Yukiho in my unit, and either a member of Project Fairy, or Mami to complete the Sinking Fleet.