I do agree with the others regarding disclosing the cameras. It does however seem a little crazy to crave privacy over potential safety and accountability in a business. This isn't the guest's personal home - it is a business that provides hospitality service. In hotels you have cameras over pools, in common areas, all around the property. You can't tell them you feel deprived of your privacy. You want privacy go in your room. Why would you come to another business (smaller business) demanding this?
When / if something happens that's the tool that will give you the facts needed to support a case. Frankly if you come to a stay and you're peeving about external cameras - you have a psychological problem or you are up to something and don't want to be seen. This is something i believe hosts should have one view on and that's to cover your ass. Have cameras everywhere just like a hotel. This way its normal. We cant have hosts thinking they are guests. Act like a host and protect your investment and and property and by extension the guest.
You only want one time some guest show up claiming little bobby or britney slipped on a deck and is suing you or AirBnB - now you wish you had footage from a camera. Protect yourself, your business and as i said before - your guest.