There are a lot of people out your way with varmits- we have our own here too. The best way to keep them safe- yet free range, is to provide a safe coop and train them to coop up at night. My set up is my barn, where I have an automatic door at ground level that opens after dawn and closes after dusk. In addition, they have a high level they can walk in and out over 6 feet above the ground to get in and roost - in the eves- safe fromt he owls and the foxes can not get in and harass them. Raccoons could get in if tremendously inclined.
'The key is teaching them. I put my young birds in a caged area in the barn for a number of weeks so they get used to this place as home. Then, I let them out in the late afternoons for a while, ensuring they go back in the pen in the evening. After a while, they will come in on their own and go in the cage- that is home. Then I shut the door on the cage and they are in the barn, secure but you can imagine, worried and running back and forth trying to get into the cage. I watch them checking after dark to be sure they get settled, but eventually they fly up into the eves with the others and then it becomes routine. It is a little bit of a process, but once done they are pretty care free. If you free range, you will have losses! Goes with the territory.
Go to my website and down load my free ebook for tips on this and other stuff with guineas. Joining guinea fowl international is great too- they send lots of information.