Laos is relatively fuss-free, Singaporeans can travel visa-free to Laos for 30 days or less and international drivers licence is valid there for 1 year. No car permit documents are required and car insurance costs 300 baht a week (under S$13).
Singaporeans can travel visa-free in Myammar for up to 30 days. However, foreign vehicles require MTT permission or authorized Travel Agent registration 4 weeks prior to arrival at the border. International Drivers Licence need to be converted to a local Myammar Driving Licence prior to arrival as well, apply via mail to Road Transport Department in Yangon or Naypyitaw, it costs USD$20 and is valid for 5 years.
Vehicle Permit (this one is for bicycles) from moz.travel
Singaporeans visiting Cambodia for less than 30 days do not require a visa. It sounds hassle free especially if you are travelling across the border by bus, motorcycle or tuktuk. However, if you are driving a car, you will need to purchase car permit and insurance to the tune of over a hundred US dollars at the border and it's only valid for one week, have your car related documents ready.
Not only that, international drivers licence is not recognized in Cambodia, you will have to apply for a licence conversion that will cost you something like usd$35 and take minimum 1 month to process. Luckily, online applications are now available so you can apply for a licence conversion before arriving at the border. Cambodian driving licences have a validity of 1 year or 3 year period, it's quite troublesome to keep track of the various validity periods.