Topband: Balloon lifted wire Antenna?

[F5vjc]

I'm going to have a go with a 3/8 wavelength (for 160M) wire, lifted
by a 2M helium balloon during the summer months. The first 40' of wire
will be supported vertically by a fibre glass mast then the remaining
156' by the balloon.  I have a ground plane in place already and will
use a manual tuner at the base to 50 ohm coax, I expect to use this
antenna on other bands besides Top band. What is a good type of wire
to use, obviously flexible, not too heavy but good copper content, or
would electric fence cord (with woven in stainless steel strands) be
too lossy? looking for any tips advice etc.

73, Deni
F5VJC