Thanks Tod. How about once on an ED visa, will I need that TM.30 form for anything? I live in Bangkok at On Nut. Only reason I ask is that my landlord doesn't live in Bangkok and not sure how easy it would be to get IF I need it.
Book a bus ticket to Cambodia out of the country. It doesn't need to be a flight out. Even if you don't use the ticket it's only $20. Or book a cheap Air Asia or other budget airline flight out of the country, there are cheap flights to many place.
The other option is to book a flight into the country that is flexible and you are able to change dates. So for example book to leave just before the 30 days and then change it to the date you are actually going to leave once you arrive.
Thanks for the input everyone. My wife's company said they can provide the business visa without leaving the country. We will apply for the extension of stay for medical reasons once that visa is up. Thanks again everybody!
English. Just needs the address of person inviting you and a copy of their passport and says something along the lines of "My friend.....will be staying with me from x date until x date at x address and will leave on bus to Cambodia.