Good looking job on the mount!
I sometimes assume too much, so I'll throw this out for those who may not know: RF only travels over the surface of a conductor, not through it as electrical current does, thus the importance of the flat strap Unseenone is using in his great installation.
As for counterpoise wires, I have experimented with different lengths and diameters and have found lengths starting at as little as 1/10 wavelength to be effective. I have also tried wires electrically grounded, earth grounded, and at no ground potential, and found that the counterpoise performs well with the exception of electrically grounded, where it has the potential of picking up 60hz hum and transmission line noise from motors and switch gear. Try to remember to treat electrical and RF grounds as two distinct systems
I have also played around with different diameters of counterpoise wires and not found a great deal of difference in performance except when I tried 30 guage magnet wire, which was apparently almost invisible to RF.
In short, almost anything conductive will work as a counterpoise as long as it is at RF ground potential. Don't overlook electric fence tape either. I have a dipole I made from it and it works great, rolls up small, and is broad-banded due to the multiple conductors and wide layout.