There may not be a technical law out there addressing this, but the Montana Constitution and other common law tort doctrines would be able to help.
This may be deemed a breach of the use and enjoyment of the property as he is now 'occupying' the space internal to the residence.
Not sure the reason for the cameras other than to weird everyone out. Call to discuss.
This is a violation of your rights under the Montana Residential Landlord Tenant Act. It also may be a criminal invasion of privacy. It is actionable under the MRLTA and you might be entitled to damages and other relief.