I ask this every time I travel to a new country: what can I expect there as a dark-skinned Westerner?

I ask this because I belong to a very small segment of travelers, i.e. I am 100% Western (European) in behaviour, attire/clothing, attitudes, beliefs, social norms, cultural cues, etc. but in appearance I look South Asian/Indian (and I rarely/never meet people like myself in the countries I travel to).

I'm aware this can sometimes cause innocent confusion, but I'm concerned whether it could cause issues such as people treating me differently due to a stereotype they have about a country/ethnicity with which I only share some superficial traits. In Poland every place I went to eat asked me whether I could eat pork - that's fine - but I have heard of certain places which don't let dark-skinned people access certain bars/nightclubs... is there anything like this in Cambodia?

Do I need to be aware of any danger in addition to what other (white) Western tourists could face?

How do Cambodians generally perceive South Asians/Indians (both people and officials (immigration officers, police, etc)?

Are there any cultural etiquettes/norms I should follow in order to show more respect and increase the likelihood of being accepted by Cambodian people? Or to stay out of trouble?

I have been invited by a university friend in Phnom Penh for one week so will be staying at her place and not in the typical tourist resorts/groups which may be less risky. Obviously since it's her country she says it's very safe and I have nothing to worry, but I thought it's worth hearing more opinions.

I wouldn't expect you will have any difficulty. Cambodia, in the area of Angkor, is very cosmopolitan. There are plenty of people from India as well as many westerners who visit the temples. Just be respectful of the culture and you will be fine.

I have several friends who are of Indian ethnicity who travel quite a bit who have never reported anything that unusual during their travels. You might indeed be perceived somewhat differently than the usual white western traveler but that is your lot in life if you live in the West anyway so why would you expect it to be that different anywhere else? As Kathie posts, respect the culture and you will be fine.

"I ask this because I belong to a very small segment of travelers, i.e. I am 100% Western (European) in behaviour, attire/clothing, attitudes, beliefs, social norms, cultural cues, etc. but in appearance I look South Asian/Indian (and I rarely/never meet people like myself in the countries I travel to)."

It seems to me that you'd have to ask those who describe themselves as you describe yourself to get anything like a satisfactory answer.

But I'll add that many of us have traits that might appear to make us part of "a very small segment of travelers" in places we go. Looking at me many people see an old, gray-haired white woman alone, traveling in places where there are very few others that fit that description. It never occurs to me that I don't belong there and I think that attitude is contagious. I'm invariably accepted after an occasional brief startled look. My advice would be to forget about the difference and carry on.

Wikipedia deals with the ethnic and racial makeup of Cambodia:
https://en.wikipedia.org/wiki/Ethnic_groups_in_Cambodia
My minimal and unscientific experience in Southeast Asia (not including Cambodia) suggests that you will be seeing people that look a lot like how you describe yourself.
In Vietnam I was an obvious and distinct tiny minority (full-fledged WASP with a thick white beard that provoked occasional amusement.) It didn't matter. On these issues, overthinking can make you your own worst enemy.

"...overthinking can make you your own worst enemy."

Indeed. The cure, cultivate a smile. I've found having one to give the best return on effort. It's nearly impossible to not have a stare turned into a smile when used properly. And I'm not particularly smiley person but people interested in me amuses me so it's become a useful habit. Everyone feels better. Sappy but true.