Hey Max,
It's been a while, but I used to hunt Sambar quite a bit. From all my years of trail camera work, I'd say sit and wait is not really a worthwhile option, you could get lucky as I've had mature stags visit wallows during daylight hours, but it was always random and no discernible patterns.
Mind you, this was just where I hunted, where you are, sit and wait might be the better option.
Preaching trees or scrapes were far more frequently visited, but if I was to set a tree stand, I'd probably look at the trails leading from bedding areas to feeding areas.
Personally, my preference was to stalk through the main feeding gullies during the last hour of light. Areas with well browsed stands of Prickly Coprosma were my favourite as they provided good cover.
Best of luck mate, you won't shoot them at home so get amongst them and the more you're in the bush, the luckier you get.
I did manage to take one Sambar with my longbow, here's the link to the story.
https://www.tradgang.com/tgsmf/index.php?topic=97053.0