in addition to this thorough reply any extension you buy and receive will not include re-entry privileges, you'll need to buy a single or multiple re-entry permit after your extension is inked in, and similarly for a Non OA on the following free year stamp after the visa expires.
You'll need to make an appointment for the Vientiane embassy and you can do that online via their website and as well you're going to need a written diagnosis and treatment plan from your dentist, make that document look as official as possible on letterhead with seals and the doctors licensing number blah blah blah
Anonymous participant consider that a freelancer is somebody who works for themselves but has clients, do you feel you qualify? On the other hand you may be able to state that you invest/work remotely and tour around to get ideas and inspect for investment, do you have a company set up?