You can't see your character in the mist? That's odd... I've never had a problem with that. Sounds sort of like some of the issues with night in GSC...
Are you using a Game Boy SP, by any chance? If so, I highly suggest that you turn on the backlight, regardless of the time of day. I've found that the normal lighting tends to be highly inadequate, even in comparison to the lighting of the traditional GBA. Other than that, I'm afraid I can't really offer any helpful suggestions (other than to buy a light for your Game Boy if you're not using an SP).