I matched obstructions to the edges of the buildings and made footprints +2m from that.
There's more large farmsteads than small ones, so for efficiency's sake I changed the default to be large.
I'm thinking the "height" part of the footprint is obsolete? And I think it only needs to be redefined if you change the footprint shape from circle to square. So I deleted most heights. (The Carthage farmstead had height = 6 instead of 8, but I can't see how that has any logical connection to its art compared to other civ's buildings. I think the selection box for everything except fields uses the artwork (in some way; I don't know the details) rather than the footprint.)