Super Mario Sunshine - modding?

[dlfon99]

So, after digging in Mario Sunshine, I discovered the game has a duplicate model of each map and commonly used object for each mission. Would it be possible to have a different map for each mission? What I'm getting at is: through applying mods to the ISO, can we replace Bianco Hills with "the grass world," with each mission serving as a different level entirely? Can we play it through Nintendon't or other loaders?