It’s up to customs how many times after 2 times they let you in. I read many stories of people beeing denied entry this year. If you have time to make a proper visa, I would do so
Sorry I misread and thought you wanted to stay in Thailand for 60 days, but still same, you need an onward ticket. It may or may not be asked by airlines, a bit if lottery. As another replied below, if you plan to go ti Cambodia better buy your ticket now, so you will travel stress free
You have to have an onward flight within the first 30 days (I will try to find again where I found the info), because I think the logic is, they can’t allow you in for 60 days not knowing if for any reasons they will reject your application to your VOA