At those mild temperatures and while on the move during the day, I would be comfortable in nothing more than micro light and at most light smartwool baselayers. Definately not expedition weight.

Staying dry in snow when temperatures are near the freezing point is most important. WB shell pants over baselayer with WB gaiters. Waterproof boots and overmitts should not to be overlooked.

Properly fitted gaiters will not allow snow to be pushed up from the bottom.

Ditto on the insulated coat and pants to put on at the end of the day or at stops. And don't forget a nice warm toque for sleeping and day use.