We have a working assuming no more surprise inaccuracies setup!
There's a lucky coincidence which might be the only reason this works at all; an instruction I'm forced to use corrupts the stack pointer such that a POP will return A8C5, which is right next to the addresses I need to activate debug mode. Of course, that doesn't change the fact that I need to somehow fix the stack pointer before I hit the return instruction, or else everything breaks.
The current setup requires 78 coins and 22 hearts. There are enough blocks in course 4 that I can potentially get all the way there just from random drops, although that won't be fun to manip. As for the hearts, I can pick up a large one during the course 3 revisit without going too far out of my way. I'm still a few short but there's a couple of places I have in mind to pick the rest up. For now I've just used the other debug mode for testing.
Something I didn't see coming was that I now need the waves on the Rice Beach map to be at a specific point in their cycle, and waiting for both that and the 256 frame global timer to line up together costs a ton of time. I thought I could cut out some of that by returning to the world map and re-entering, but that sets the current course ID to hex 30, which is outside the normal range. Trying to enter that course or select a different one will either force the game into an infinite loop or halt it on an illegal instruction.
Other possibilities I'm looking into are 71 coins/34 hearts (requires at least one more big heart) and 36/01 (avoiding that many kills causes a lot of complications), either of which would reduce the wait time on the map screen.