If the tenant changes locks, that should be a lease violation that deserves a written warning and a demand for copies of the keys within X days.Based one what you've said, my state laws, and my policies, I would write the tenant a notice that includes the state law and that the Tenant cannot deny entrance, even if they are not home.

Why not build your house and put in a basement with a separate entrance.  

I'm currently searching for duplex or SF house with an in-law suite (separate room and bath with private entrance).

Two separate kitchens, laundry units, entrances, and living areas.

it's about 50 feet of dirt with minor grading, as well as two breakouts for entrance, it doesn't look like there's gutters involved , either gravel or pavent for the road with a swing out gate to keep traffic out. i know it's tough to ballpark , I may have to front the cost, curious what type of contractor to reach out to for this work or what kind of cost could be involved .

Now having said that if you put cameras anywhere other than covering outdoor space such as entrances then you are not going to have many guests.  

Basically a 1 bedroom (with its own entrance) apartment without access to the house

It is 3 bed 1.5 bath upstairs and 3 bed 1 bath downstairs with a kitchen and separate entrance.

Both properties have 7' privacy fences and we have a private entrance leading to our property.We've provided the tenants with a pet addendum, however there's no language in there protecting our dog should anything happen to their cat. 

You should be able to put a wall down the middle and add a separate entrance.