I've taken both a rodent and bettas from alaska to new york in wintertime and it was very stressful. All but 2 fish froze and the chinchilla was a basketcase. I take it you are driving? How long does it take to get from TX to MN? It IS doable, if it is the only option. I ended up having to hold the remaining fish in a very small animal carrier on my lap for 10 days, under piles of blankets with the heating on full blast due to the extreme temps (-40F).
Uniheat has 72 hour heat packs. I had pretreated water in milk jugs as well but it froze soild in the backseat
so when I did stay in a hotel, I ended up using canadian water with stress coat.
I had most of them in coffee cups that way they had access to air as opposed to using shipping bags.
also, bring a syringe or turkey baster to suck out poops incase you cant do a water change. Unless you have some really freaky weather along the way - you should be ok.
Not sure about rats but chinchillas like colder temps so she was OK in that regard but OMG she was nuts for days after the trip ended. I dont think she liked being in her cage in the backseat of a car for 2 weeks straight
Its already been below freezing here, so don't forget the heater