Is bus (travelling between Sapporo-Hakodate) safe to ride during midnight especially in winter?

Thank you!
I'm comparing the price between riding train and buses to/from Sapporo-Hakodate.
I haven't decide whether to get Hokkaido JR Pass (5-Day or 4 Days flexi). What's your recommendation ?

Is it worth getting the JR Hokkaido Pass ?

My 5N6D itinerary will be as below:

1st day - New Chitose --> Otaru
2nd day - Otaru ---> Hakodate
3rd day - Hakodate ---> Sapporo
4th day - Sapporo only
5th day - Shiroi Koibito + Bankei Ski Area
6th day - Sapporo ---> New Chitose

I'm kinda confuse with JR Hokkaido Pass coverage
*im going next February

This post has been edited by Ovenly by J.: Dec 13 2018, 05:15 PM

My friend suggest me to put our last night near to the aiport as my flight the next day is 9.20am, to avoid transportation issue(worst is winter storm) to the airport, do you think is it fine if I remain my stay in Sapporo city and catch the earliest train to airport?

Alright, thank you so much!