On my DM5 Pro (DM10 Pro is the same size):
From foot to foot is 3'8" and front to back of throne is 3'11", farthest point of ride to farthest point on hi-hat is 4'9". My back is to a wall, so I have an extra 6" behind the throne (and since I have an entire room for it, I have plenty of space around the kit).
So depending on height and how you place cymbals, 4' by 5' should do it and 5' by 6' should be comfortable.