I don't think it's any different than getting a tourist visa, except that you need to do this visa in your home country, or pre-covid in Perth Australia you could do it too. So you can't go to Cambodia and get the STV.
Avoid entering from Suvarnabhumi Airport (BKK), try entering via Phuket or Chiang Mai, as they are friendlier with people with many stamps. Suvarnabhumi have a history, which began far before Covid, of making it difficult for people with many stamps to re-enter Thailand. If you have no choice and have to enter via Suvarnabhumi, make sure to have an agent phone number who has contacts at the airport. The agent will help you bribe your way in if you are about to get denied. It's very common in Suvarnabhumi.