Speak to your local tourism people they will have an idea of visitor numbers and what demand is like for accommodation in various areas.
In the UK we can also pay for market research reports from local and national tourism bodies. So see what is available.
Check on availability of the BNB in that area - how busy are they? It might be there aren't more because there is no demand. Also check out B&Bs, apartments, hotels etc.
Even if BnB have that information, they probably won't provide it. It would be too time consuming for them to give free market research stats to everyone who wanted this sort of information