You would not need to leave Thailand.
You can obtain the non O marriage from the visa exempt entry.
However all depends on immediate plans.
Once married you can obtain 60 day extension to visit wife ...
You haven't made clear immediate plans for next say 1 year.
Seems little bit rushed. Lack of planning?
The OP Stated...."I am willing to get a marriage visa, but as I understand it, that process takes some time, and is unlikely to get done quickly"
Thinking he has been given incorrect information. Easy process
What an amazing post pretty much about nothing.
The OP is currently not married.
Even if he does marry the Thai long term g/f you have gone off on so many unnecessary tangents.
The one sentence I quoted is misinformation and basically nonsense.
You base that on a bad personal experience.
"Abusing the system" that's out there...
MANY married guys have been obtaining ME non O marriage for years and years. No issue.
If he does marry a non O marriage (single entry) + subsequent annual extensions a good option and financial requirements low threshold
Actually it's the opposite..
Getting married to a Thai and obtaining a non O plus subsequent 12 month extension is relatively simple quick process.
You mentioned gf of 10 years so yes it's an option and at 30 one of the easiest.
You refer to non O and yes for retirement requires you to be 50 yr+.
Non ED gives you a year.
You don't mention if you wish to live ongoing in Thailand or just visit Thailand and continue working/living in own country..
The easiest option is marriage
May have been the intention however has not been that way.
Many folk living in Thailand with this 12 month visa and doing border bounce for next 90 day stamp.
You can obtain the 60 anytime.
When you exit any days from 60 extension remaining are gone, however you still have a valid multi entry visa.
Don't think you mentioned your immigration office however most will give you good advice..
https://aseannow.com/topic/1307757-getting-3060-day-extension-to-current-multi-entry-non-o-visa-to-visit-wife/
My understanding is that you can obtain one 60 day extension per entry with a ME Non marriage that you have.
Happy to be corrected.
OP, not sure why you are even starting a thread.
Clearly you have a good knowledge of options.
As just post above as I type this the 60 is added to the stamp (90 day) you will be given on reentry.
You can do both.
Some folk with fast track option go through another Zone and walk back airside to Zone 2 for reentry permit.
Most attend Zone 2 and obtain permit prior to passport control.
For others note reentry permit desk at DMK is after passport control
Adding 89 days to Wednesday June 25, 2024
Monday September 22, 2024
That's your next report date.
As already pointed out ....make sure you obtain your next extension.
Your extension is not tied to 90 day reporting.
AGE....it has been asked few times already.
If 50+ you could obtain a non O-A that would actually provide almost 2 years. However requires health insurance.
Another option is to obtain a non O retirement and subsequent annual 12 month extensions.
If ever marry to a Thai you can change to extensions based on marriage.
Just a friendly tip....cut back on chit chat regards marriage. Sounds very needy in my book.
Some good advice already posted above by @timendres
Visas are not transfered.
Information pertaining to them is noted in your pp #2.
So when transferring info from #2 to your current (new pp) immigration will note that into in pp #3..
Note: realize you are using CM just note for others..CW are requiring photocopies of bank book back to last extension to check compliance for those using money in bank method. A new trick.