South bend, Elkhart, goshen for a room, there should be some available. Personally I prefer to sty in Chicago and drive in on Saturday but sounds like you need to be in south bend area longer?
If you are 1 or 2 people I would buy tickets from a scalper on game day I'd be surprised if you paid more than face value ... Stubhub in advance you will get killed but you will have tix in hand.
Other than a handful of games when ND and opponent were highly ranked I've always seen plenty of tix avalailable and even had to basically give away a pair for one season opener vs USF