Paul, I'm watchin ya
0.6mm MIG wire is quite strong, but 0.8mm would be better.
Downside of MIG wire is that the copper coating is very thin and over time, the steel wire below will rust and percolate through the copper - ever left your welder in a damp garage for a few weeks and then wonder why your weld is like seagull pooh and you need a new liner for the gun feed?
The best wire is the gold plated 'Memory Wire' used for making neck and wrist bracelets - I got mine in my local 'beads n bangles' shop - it's the one full of ladies giving you strange looks
Ever used one of these?
Drive a wheel over the base plate and drop an extending mast over the pole, voila, sturdy mast at 20 foot.
Made my own for operating on Amateur Radio VHF field days.