Hey mate, I did NC500 in the Summer with my partner - she wasn’t too keen on camping so we did B&B’s and spread it over 6 days.
On my search I didn’t come across many issues with minimums stays and I used a mixture of Booking.com and AirBnB. Would also suggest double checking they have somewhere to store your bike/can bring it into the room. We had only had one place (the one day it was pissing it down) who didn’t have any bike storage and wouldn’t let us take it into our room.
Like the millennials we are, we have a written a little bit on our blog about it: http://www.weekendwatts.co.uk/bikepacking-the-nc500/ and there is also a video on there we made too - if you want to know specifics where we stayed I’m happy to drop you a DM 