I suggest giving it a shot anyway. Use your moonjump code to go very high and try to get through the barrier to Corona Mountain. If you succeed, I will be able to make a video of me completing the entire game with the minimal number of Shine Sprites possible.
I was talking about inside Corona Mountain but I realized how you meant it. So yeah, I tried it and I got through. EXPECT apparently the game doesn't trigger the entrance until the gate is off, so this pretty much ruins your plan. But isn't there a certain mission that triggers the flood or is it a certain number of shine sprites? I can't remember.
Edit: I managed to get out of level in Ricco Harbor. It's actually more interesting then I thought. Apparently you can get really close to Gleato Beach. Anyway, there are 2 other findings I've found so far. One is an odd stone structure that is placed high above the mountains. I'll check if this is viewable in the normal level. Behind it there are palm trees, I'm guessing it's supposed to be Pinata Village (Sorry for spelling). Either way, I find it interesting that there's an actually high level of detail in something that you can barely see. And BTW neither the stone or the trees are accessible, unfortunately. The other thing I found is an odd slope under the gate which leads to the blooper surfing level. Basically, if you get in there while it's closed, for some odd reason there's an invisible slope behind it. I can't explain this...maybe there was something planned behind there but they had to hide it with the entrance to the level?