5 months later...
I finally found time and motivation to tackle this beast :). I've spent a couple of days rewriting some programs and I made a fast 'preview' of what the eventual tas would look like:
Click!
Recorded using snes9x 1.51 with the following pro-action replay codes:
82E99EA9
82E99F02
This movie gets all 9 normal Iris Treasures in 36 floors and grabs a Providence and escapes at floor 37. Naturally, the actual tas will go all the way to floor 99 and defeat the jelly, but I wasn't feeling like optimising another 62 floors when the first 36 weren't optimal to begin with.
The strategy I will use in the actual tas will aim for an Iris treasure every 10 floors, so I will have the last 8 floor to worry about an item/spell/weapon to kill myself with.
As for the version of the ROM and emulator I'm going to use, I'm not sure yet. For clarity: since this run will probably last less than 10 minutes in NTSC timing, the timing difference in PAL will be 2 minutes at most. For a normal-mode speedrun, which lasts about 3 hours in NTSC, the difference in PAL is ~36 minutes.
Fun fact: the probability of finding 9 Iris Treasures in 36 floors is 2.5459 e-11