Sorry, but characterizing Freedom to Roam as allowing people “camping in my backyard” is indeed FUD. Words like “my backyard” have a reasonable definition, and you can’t just redefine them at will (i.e. redefine “my backyard” to mean “my whole property”) to make the statement technically true.

The dictionary definition is "the area close to where one lives, regarded with proprietorial concern"

Er, no. A yard is a single open space. Your backyard is the single open space behind (i.e., not in front of) your house.

In america "backyard" often refers to an area extending beyond ones own neighbourhood. It's where the acronym "NIMBY" (Not In My Backyard) comes from.

The OP could indeed be objecting to unknown people camping anywhere near their property, even off of it.

As an American, yes backyard can mean the general area where one stays, but in the specific comment above, I also took it to mean literally in someone's backyard.