CotG hack in two CDs?

Hi! (no, i still have to wait before i can continue the hack)

I was considering the idea of making CotG in 2 different ROMs... (if i'm not wrong i heard Tsushiy made the same with his hack)
In the first place because i need more than 383 monster slots to do all what i want, changing rom i can swap all what appears only in WoB with different stuff(monsters, sprites, maps...)
Theorically Madsiur's tools still wip should be able to deal with that, but i dunno what to do, in the case i'll be able to finish before him, yet it's quite interesting the idea of having available 2 extra empty Wo? maps... It could also allow the use of 2 extra chocobo powers and many other stuff that still have to come in mind.

In the case, after the world is destroyed and before the "1 year later..." message screen appears i'd put a black screen (like the choose scenario room) in which there's a save point (a message will tell you of saving the game because it's the end of "Disc 1") and an NPC which will ask you to insert "Disc 2" and restart the game. After that it might start some kind of brief cutscene, similar to a trailer of disc 2.

Loading the save from Disc 2 you'll still be in the same room, but since it will be another rom with changed stuff, it will start WoR story from there.

Yet there's something i don't like: is there a way to avoid that someone can load a random save file and magically access the second disc? the same for loading that save on disc 1 and being able to skip something?
I cannot tell it for sure but maybe in ROTDS 1.3 it's not possible to do that...
if that's the case, then i'd like to hear how Gi Nattak managed to do that.