I've been working in Asia for almost three years now. (Macau and Singapore)
Option 1- Are you considering moving to Cambodia and trying to work as an SM there?
Things to consider:
-Cambodia specific- This is one of the poorest countries in Asia. There is NO high budget theatre or events scene there. There are lots of dance/ cultural shows (a lot of them geared towards tourists and in conjunction with restaurants and tours.) I wouldn't think that they would have an SM calling cues, but could probably use a backstage coordinator or techie kind of person. You'd definitely need to have a resident status and speak Khmer. None of these places would sponsor employment visas.
-Thailand and Malaysia are larger countries with larger budget events. They both have large resorts and casinos. These resorts would have entertainment onsite and also be a venue for one-off events and touring shows. The company Resorts World has branches in the Philippines (Manila), Malaysia (Genting) and Singapore (Sentosa). Resorts World does hire foreigners for some of their technical/ stage management needs. English is widely spoken in these countries.
-Bear in mind that to get hired in a foreign country you have two options: gain residency and get a work permit that way and get hired "as a local" OR prove that you are more qualified than any local and get sponsored for a work permit. Extensive professional experience and a university degree are usually required to prove your qualifications.
Option 2- Are you wanting to work for an events or theatre company from your home country that travels/ tours to Asia?
Things to consider:
-Touring shows and events will go to (usually) larger cities with both the budget and audience to support them. I imagine a few shows or companies might occasionally go to Pnom Penh (rarely). Larger cities like Bangkok, Manila, Kuala Lumpur and Hong Kong will attract a lot more touring shows and events.
-Touring and/or events experience will help you get these kinds of jobs, obviously. I suggest applying at events companies in your home city to make connections and gain experience.
Feel free to PM me with specific questions.