DMH can be played on a 2’ x 2’ board, although we always find it a bit more cinematic with a 3’ x 3’ one. For number of buildings, as Harry says, 6 plus plenty of fences and some scatter to add cove and that Old West flavour.
Here’s a 3’ x 3’ DMH set up we played a few years ago (it was also used for a 7TV game, too)
Alternatively, let the scenery provide cover, as in this slightly adapted DMH game for 4 players.

RMZ