PSO - Seasonal Travel

Has anyone found a way to define seasonal travel in PSO.

For example, during the winter in mountainous areas, there may be extended travel times due to a combination of weather and potentially traffic cause by winter sports enthusiasts! or even certain routes may be closed for extended periods.

These could be defined by a Travel Time Profile using weightings and barriers, but there does not appear to be a way to define a time window for an entry or a profile (other than time of day or day of week).

The customer could simply have two Travel Time Profiles, and switch them over on specified dates, but this could lead to missed appointments or SLAs if the winter profile did not allow all the travel that was originally planned based on the summer profile to be made.

Not sure if there is a out of the box solution to this, but any thoughts would be appreciated.