What are the kinds of headwear that are acceptable for a non-Sikh man to wear in a Gurudwara?

brief question: What is the minimum versus the recommended head wear for a non-Sikh non-Indian adult male to wear at Gurudwara?

I am not Sikh, and although I do respect the ten Sikh Gurus, I am secular. I am a westerner. In my hometown of Greater Vancouver area (BC, Canada) as well as in Southeast Asia I observe the following...

1. Gurudwaras at special functions and Sunday langar offer simple white handkerchiefs to male guests (both Sikh and non-Sikh) who do not wear turban.
2. Indian young men often wear very casual kerchiefs of same. Sometimes I am a bit taken back, as if they are mocking by wearing eccentric attire accompanied by less than stellar behaviour in a house of worship. Or maybe I am a just a rather conservative old man. Who am I to interpret what is acceptable headgear? They are not drunk or obscene yet somehow I view them as juvenile delinquents. And American Muslim converts wear baseball caps to Masjid, so why not Sikh teenage boys wear rock star kerchiefs?
3. Most Sikh men wear full cotton turban, 'from scratch', and if at Gurudwara simple or no design, nothing 'flashy'. This is different at parties, weddings and sporting events where I see some Bollywoodish turbans.
4. Non-Khalsa Namdharis wear smaller, very different looking turbans, usually white
5. Sikh businessmen in Thailand tend to wear token turbans (i.e. not made from scratch every morning) in plain colours, especially black. Some appear to be a kind of cap really.
6. At the Dhaka Gurduwara in Bangladesh I arrived for Sunday service wearing a woven beret. Even though my then long hair was flowing out of it, I was not asked to tuck it up nor replace it with anything else. I was also under the impression that Muslim men's caps were acceptable heard wear. So, which is more important - the intention of respect or some technicality of whether all head hair is gathered up and covered? I would sincerely like to know. If it is a technical matter then any cultural standard (Jewish, African, Rasta Caribbean etc) should be acceptable as long as the hair is covered. Even a blonde wig? Or do Punjabi cultural norms apply before universal religion?
7. Why do Sikhs not wear linen turbans? I prefer this fabric to cotton for many reasons. Is there any prohibition?

The reason I am asking this is because when in Malacca, Malaysia I attend a yearly festival there, and I want to be properly dressed as I feel silly wearing a handkerchief. Also, I want to visit a Gurudwara on a shaheedi feast day such as one for Arjandev (my interest is more socio-political than religious). I wish to behave respectfully but have no pretenses to be Sikh myself. So, I was thinking of just getting one of those quasi-turbans that are popularly worn by overseas Punjabi Sikhs integrated into Thai society (often they even have Thai wives who convert). There is even the super mini version which is really just ... (more)