Jeremy, KC5TEK wrote:
"I`m not terribly concerned with rust as I plan on painting the whole
assembly anyway."

My 2-meter groundplane uses a GM telescoping car antenna as a radiator
and steel shelf-support channel from Home Depot as radials. These are
solid rust after many years and they still work fine.

Groundplanes are best for fixed locations unless you are using a vehicle
body or the like for your groundplane in a mobile application.

Commercially, the simple whip antenna worked against a car body has
almost universal acceptance.

For workboats to get a little height for greater line-of-sight we used
coaxial antennas. The vertical whip was half a diploe. A brass tube
skirt served as the other 1/4-wave part of the vertical dipole. It could
be elevated as high as convenient and worked as well as a groundplane
but with no risk of poking out an eye on a tossing and turning boat. My
ARRL Antenna Book has no construction article for the coaxial antenna. I
wonder why?

Best regards, Richard Harrison, KB5WZI