Jpole antenna made with wire instead of pipe element spacing

[darklife]

I've built jpole (1/2 wave end fed dipole over matching stub) and they worked well with conduit, copper, whatever type of pipe.
I realize the larger the diameter of the antenna elements the bigger the bandwidth, but this brings me to questions..

Does the diameter of the elements and the spacing between them interact in a way that it should be carefully planned out?

For example an antenna made with standard copper tubing for 145MHz according to the calculator on M0UKDs website has a
small and large cactus leg spaced of 4.5cm and it says that it's not critical.

What if the diameter of the elements were the size of stainless steel antenna whips at the same spacing? Wouldn't that dramatically
change it because the stub is suppose to be looking like a piece of feed line electronically?

I am asking this because I was making a very lightweight Jpole using the same calculators everyone else does online but instead of copper tubing I am using a J shaped PVC setup and lamp cord wire as the radiator glued to it.

Yes I know the Slimjim antenna variation exists but I wanted to build a Jpole quickly without the weight of the pipe material for a project that could be bottom mounted as I didn't have any 300 or 450ohm ladder line.

My guess is skin effect of fat radiator materials would still have the same distance effect of thin materials from the outer diameter? Besides velocity factor altering element length?

[antenna]

It would affect the tap position.  The bottom matching section is an open wire transmission line and the characteristic impedance of the line is a function of the wire diameter and spacing just like twin lead and the like.  IIRC, increasing the characteristic impedance moves the tap point up a little. 

I think part 3 of this gets into it
https://antenna2.github.io/cebik/content/vhf/jp1.html
https://antenna2.github.io/cebik/content/vhf/jp2.html
https://antenna2.github.io/cebik/content/vhf/jp3.html
https://antenna2.github.io/cebik/content/vhf/jp4.html

This one is pretty cool too
http://pabut.org/JPOLE.HTM