I am a commuter from Austin to Rochester, but my drive is about 50 miles one way vs the 90 miles from Rochester to Mankato. So I can't speak to that size of a commute. There are a lot of people that come from long distances to Rochester every day, so that isn't uncommon. However, many coming to Rochester have commuter busses as options. I commute with my husband, so between having good conversation with him and listening to audiobooks, the commute is pleasurable.
Things that may be helpful when making your decision:
*Most of the traffic on Highway 14 would be heading the other direction, especially early in your commute. I'm not sure what traffic is like going into Mankato.
*You would MOSTLY be driving on divided highways (2 lanes each direction), but half of the distance of your commute would be with stoplights and no "typical" exits.
*You would mostly be driving at 65 MPH, so it wouldn't take many more minutes than miles to drive.
*I am not sure what the parking situation is for those driving into and not living in Mankato. That would have to be a consideration if you were working in Rochester.
*Speaking from one commuter to another (especially one from Texas), winter driving should be considered. It can be very difficult some days.
I am tagging @lindseymarx as she works on the Mankato campus and can maybe share a bit more about that community.