Is there a way to filter weldment face edges from dimension quick snaps?

I've got a weldment with rectangular tubes.   I'm finding that when adding dimensions to the drawing, the snaps are just as likely to grab the edges of the face/radius than they are the actual edge of the tube.   I found that I'm able to hide the edges, but the dimensions still snap to them.

I'm finding it rather hard to tell which I'm snapping to, as the highlight only shows up for a split second, and after mousing over the edge it doesn't seem to want to snap back to it. 

Is there a way to filter those tangent edges from the snap, or maybe show a better indication of what I'm snapping to?

Image shows what I mean.   I'm just as likely to get either dimension, but I would only ever want the top (edge to edge).