After some research on the internet regarding the Z-brackets we decided to follow Dan Checkoway's method for drilling these to get a perfect fit between the tank and leading edge.
Started by drilling the center holes as per Dan's instructions on http://www.rvproject.com/20020605.html and bolted the brackets square to the spar. The remaining holes where then back drilled from below through the spar.
The platenuts were then attached to all but the inboard bracket and bolted to the spar, ready for the tank assembly to be installed.
