I would use a basic loader and check HIMEM. This will be automatically adjusted for more roms.
Then compare that against the max address you use and report an error if HIMEM is too low.
Then you will always know when it's safe to load or not.
it's a good idea, but throw and error and not execute the game is less nice than preserve #Axxx-#BFFF till the last minute where you ldir this memory and execute the game!!
Not always is possible, but we always can take liberties like remove some code (like erase screen on bitume), compress code, or if there isn't another solution use the second bank!