@Paco *****
, you can apply for a new in-country visa when you enter Thailand on a tourist visa or visa-exempt (for which you are eligible). You cannot apply for a long-term extension directly from tourist entry. You need to apply for a Non-O visa inside Thailand at the immigration office or outside Thailand at a consulate/embassy.
You can apply for a re-entry permit (multiple or single entry) even when you are under consideration period, but the re-entry permit is valid the same as your current stamp. So in this case, your re-entry permit (usually single is enough) is valid until the under-consideration stamp date.
If you need to apply for a re-entry permit on an under-consideration stamp, you also need to talk about the trip schedule with the officer, too.