Thorp Air Command - T18.net

I'm about to start the building process of the partially built S18 I picked up earlier this year.
I intend to have fuel tanks in the leading edges of the outer wings as some of you have done.
The plans that came with the build are late 1980's plans and there is also a specification from an Australian Aeronautical engineering company for the Fuel tanks in the outer wings.
I think that some of it is overkill.
They have specified .065 material for the main spar web.
I would be happy to go to .040
Have any of you seen the need to upgrade beyond .032 for the ribs and spar web when building these tanks?

In case you haven't seen them, I believe there are wing fuel tank plans in the T18 newsletters. Maybe you could at least compare the two plans to help you make some decisions.