For example action replay (2 and 3) are 128KB/256KB of size, and require the actual hardware for the functionality (such as capturing the HW register writes). These will not work, even if you could stuff it inside the ROM.
Even if you somehow would manage to fit the monitor app inside the ROM, there's a good chance it actually uses data area to store it's variables, and fail horribly when stored to read only memory.
Even if you would somehow get a monitor app that fits, doesn't require any magical hardware, and works from ROM, you'd still need to patch the KS ROM to actually activate the monitor (that is to modify it to hook the level 7 interrupt).
Possible? Sure.
Likely to ever happen? No.
