I easily found accommodations along Le P'tit Train du Nord at the end of the day, but I began riding south from Mont Laurier on Labor Day, so most folks were going home that day. I'm sure July is a different matter, and on weekends in July things will be tighter still. If you're looking for indoor accommodations, it would probably be useful to look at Airbnb now as well as in the upcoming days to see what availability is like, and then decide accordingly on the necessity of making reservations.