>>>Smaller diameter tube would necessitate a thicker wall, right?

Yes, but it is a very bad relationship. Always go for bigger diameter than bigger wall thickness. The larger diameter tube is always lighter for the same given stiffness.

Indeed .07 and .08 " are good wall thicknesses as long as you mian diameter is at least 1.5" or bigger.

If you get 0.07 by 1.5 than you'll have to support it in the middle to prevent buckling but on a N6.0 you can tie th pole to the foil and solve that little issue that way.

Good luck.

An inch = 25,2 mm

Again Ideal pole will be 40 mm by 2 mm tube. Or get very close to this one.

If you can't find that

go for 35 mm by 2.5 mm or 3 mm and support that in the middle !

If you can't find that than look harder.

If you find something and you're not sure wether it will work than contact me and will do the math.

Wouter