Gonna add side rails to my boat trailer this winter. How much clearance am I looking for between the boat sides ( Square front jon ) and the rail. The trailer has a roller that the center rib runs on that sits about 6' back from the front the boat when properly trailered. Should I keep it or chuck it? I like the idea of planks on the bottom if just for walking on. Currently the back of the boat sits on 4x4s.