Topband: Perimeter Elevated Ground System Wire?

[PaulKB8N at aol.com]

Gang,
 
I have a clear area about 31' by 31' to put up a short 160M vertical  this 
Fall.  I am planning on putting up a 40' top loaded vertical in the  center 
of this box with an elevated ground system 8' above the ground.  I  am 
planning 4 radials to the corners of my box (which are only 22' long)  but I am 
planning on attaching a perimeter wire connected to the  ends of the four 
radials.
 
My question is whether a perimeter wire attached at the corners will  be 
helpful, or should I use individual perimeter wires each connected to  the 
distant end of each short radial to create four 53' bent  radials?  Or, I 
should have a single wire that is attached to the  perimeter wire for a 146' 
one-turn spiral radial?  
 
I'm not completely limited to four wires, I could add more inside the box,  
but four is the most XYL-friendly option.  Thanks in advance for your  
responses.
 
Paul, K5AF