This is my yard as seen from the back deck. As you can see it's a pretty big, empty yard. The only feature of note is the decomposing stump in the center of it.
This is the back yard seen from the south east corner of the back yard.
Here I've laid out the walls to show where they would be taking up space in the yard to show how much space we would have left afterwards.
6m is plenty of room for a lunch, which is nice and 9m is easily enough for linear line drills.