I've done most of those activities in the Oz winter.
The winter time is a much cooler version of summer with temperatures below the 100f + that they get at Xmas - nearer 60/70f and just as sunny. Much more pleasant for a traveller from the frozen north.
The Bridge Climb was a hoot - laughing all the way. But climbing trees is an invasion of Spider Territory. But at least the tree snakes eat 'em.
Not for me.