I was concerned also. The hollow coaming is about 14" wide.

I ordered a 5 gang organizer specially made to my specs from Garhauer and secured it temporarily on the coach house. I made a temp plywood mount and put the clutches on it just as it would be when finished.

So,, now both the rollers ahead of the coaming are in the right place as well as the clutches behind the coaming.

The scary part is cutting the coaming. I pushed a 1/2" dowel through the rollers and found the approximate place the holes needed to be drilled for alignment and made a large hole for each line.

Next thing I did was to cut schedule 40 PVC pipe and put the dowel in the pipe ( dowel represents the line) put the pipe through the hole and position the dowel in the clutch on one end and in the roller on the outside of the coaming and center the dowel in the pipe with paper towel or other so it's not touching the pipe.

Fiberglass the PVC pipe and finish it off.

Finally replace the plywood clutch platform with the real thing and all the lines are in perfect alignment.

Here's a link to some photos. http://www.yarussi.com/A%206%20month%20rigging%20project.html

Never done it before but it worked fine. 4 years and no cracks in the fiberglass. I would rather have found a fiberglass pipe but couldn't find any so used the PVC instead.