I'm more concerned about the radiator airflow being blocked than the intercooler.
Aren't you concerned about the lack of straight through air flow OUT of the intercooler? If the blockage from the fenderliner behind the I-C isn't an issue, why the concern about blockage in front?
Don't make the direct opening larger, it'll just pack up with snow that much quicker. Instead make a rear facing I-C air inlet that the momentum of the flakes can't turn, or make a duct that sits behind the radiator. The heat from the rad will melt the snow before it gets to the I-C fin surface.