Yeah, that's pretty much what I just emailed to Adam.
8 things per level. For each alignment the class allows, one is tagged with that alignment. Do 5 and you level.
Why 8? It's the smallest number (for space) that allows for not doing all of your options. 10 would be good, with the same constraints, but that's more space.
There's no way these would fit on the playbooks for all levels. There could be notecard-sized level sheets to track them, but who wants to print notecards? There could be an XP-playbook per class, but that's a whole 'nother thing to print per class.
Just having a master list per class, instead of per class per level, is easier, but could be a little repetitive. Also allows spamming one option.
Maybe one advancement playbook for everyone? With, say 20 options per level, with a few of those marked as class or class+alignment specific. It could even have multiple checkboxes next to each, so that every player can track their XP on the same sheet. Still kind of impractical, but having XP tracked in a shared space has some interesting social implications, much like physically taking XP for keys.