I have no experience of shooting in snow, and very limited cinematography experience, but one thing jumps out at me straight away.
Master Primes are T1.3 where as S4s are T2.
A shoot in variable conditions in a remote location with less lighting and grip equipment than a standard commercial, would definitely benefit from the extra stop that Master Primes provide. i.e. allowing you to shoot later into the evening with changing to a grainer stock or breaking out larger lamps.