One comment asked about using a dimension style that uses "no lines". I exaggerated, it does use the dimension line but that will overlap the other so it is "invisible". A video will help see how I apply it and these two dialog boxes will show what settings I used. Hope it helps...a little.
Setting the Type Parameters:
Setting the Units (from within Type Parameters):
Here's the VIDEO and the version at You Tube:
As it turns out the person who asked about this wrote a tip at the RevitForum.org that describes roughly the same thing except he eliminates the dragging of dimension values by increasing the Dimension Line Snap Distance parameter so that one dimension is above the other automatically. A nice improvement which assumes that format approach will be acceptable. Hopefully it will be! If not, the way I show in the video shows what you'll have to consider.