Tower location

Brian Raymond, can you help me out please? What is the proper placement of a Rad-A-Cage on a 2000 Outback? Are there reference points to use to dimension from? I haven't actually held the tower up to the boat yet, so I may find that it only fits in one place. Any advice would be great.
Can you also tell me how a boat cover with a cinch rope or draw string around the belt line can be modified to work around the tower legs? Does the rope have clips or couplings installed?
Thanks.
Dave Wells