Some budget minded mods I did on my 01 cat. I purchase 2 sets of 6 Roxx running board grips for a total cost of $50. I rivited 6 on each side and drilled 3 1.25 inch holes between each grip (see attached picture). I drilled the first hole with a 3/8 bit and used a cone shaped metal hole reamer to cut to 1.25 inches (hole reamer cuts a nice clean hole). If your 03 is like my 01 the running boards were like standing on an ice skating ring. I also used 1 inch square tubing to raise and move forward my bars. I added a 1.5 inch riser block to the stock riser block for a total of 6 inches rise and 1.5 inches forward which is comfortable for my hight 5'7".
Good idea... think I woulda made your "grippers" full width and cut out the middles of your holes making 1 long slot. It always in the designers eyes though, you did good.