Bring the wall into the editor, you may have to scroll in a little for it to appear.

To place these press 'b' twice and they will snap together, do this bfore starting to place.

Once you have ALL your walls placed save your level and close Reladed. 

Open the .fpe in
 
Files\entitybank\invisible wall 

and change the following LOD setting:

FROM THIS:

;LOD System
disablebatch  = 1
lod1distance  = 5000 
lod2distance  = 50000

cHANGE TO: 

;LOD System
disablebatch  = 1
lod1distance  = 1 
lod2distance  = 50000

When you restart you should never see the barrier in your game.

You might want to make a back up of this so you can re-use it for different levels, only change the LOD setting when your happy all your walls are in place or if your comfortable with changing settings back and forth.