Expand pclaim, put stone wall right in front of current plank. Leave 7 spaces empty then build another plank and then stone right in front of it. So now your base is covered by 2 plank+ 2 stone walls to fend off ppl. (The inner 2 stone walls are still useless, just forget about them)
Make sure your pclaim goes at least 15 squares past your farthest wall to avoid ppl trying to splash walls off-claim onto your wall.
Lastly, If you have torchposts set up, make sure that the torchposts range does not exceed the pclaim size or ppl can drain your torchposts ammo without having to walk up to your walls and hit them. (Just expand pclaim a bit more to pass the range it can reach, don't build torchposts farther away from walls to do so)