Welcome! The large expanses of the filler triangles are a nice spot to show off fancy stitching, but I think all the pretty piecing might be overwhelmed. The same geometric gridding of ditch-quilting the diamonds would be boring in larger blank areas.
Perhaps doing the "press 'n' Seal trick would help you decide. Cover area in plastic wrap, then draw design on and see if you like it. Faster yet, take a picture and doodle right on the picture.