There was a time when the op shop business shirts were fashionable bushwalking wear... or was that Hawaiian shirts

The synthetic ones all thats needed for lots of walking.
I'm more thinking something other than cotton but getting up around the weight of the KG shirt (190g/m). I guess insulation is more important when wet (here in tassie) but ive found that anything thicker than the lightest thermal doesn't really dry overnight anyway (without help or improving weather)
There are lots of options as per macpac/mh (thanks), everyone seems to have a light, 'quick dry' synthetic option but not heavier synthetic or even blended.
The design something similar to the KG but with tab/gusset cuffs, vents , pockets not necessary, closed front..
Those arm gaiters would be handy if you go looking for scrub

The suicide suit may work with a helmet (wombat style..)