don't go at night. pay attention to the blue swirls. raze the land between you and your target location. use camp fires if you intend to stay at night. Notice fires, plural. Or if you have access to Bonfires centralize some and fan out camp fires. Remove or destroy any object that breaks your line of sight. And don't sleep there.

And you are correct.
BF has an endless supply of reinforcements it can teleport on a whim. Not rapidly, but constantly, that is scaling. Have a day!