You guys will probably laugh, but I just use a tarp, some bungee cords and a plastic garbage bin over the top. Been doing this for more than a year without any issues - Been through HEAVY rain, storms heat, frost. In other words typical Melbourne weather
No condensation so far, but my mount is sitting on a bunch of concrete pavers, rather than grass. I think rust and dust will be a problem, but I think I have just as much of that when the mount is in my shed.