Solved - I'm an idiot! I didn't notice, at the top of the form you can check "foreigner" - and then it asks for your passport & nationality. I've registered.
I'm American, and I entered Thailand from Hong Kong with my emergency U.S. passport with no problems. I did not go to my home country. Should be fine, my emergency passport was fully accepted at immigration, airlines, hotels, etc. Carried the previous one along with it, but nobody ever had a problem with the emergency passport.
We bought a condo in Bangkok during the past year, to live in, not as an investment. As others said, costs of ownership are minimal, we have barely any monthly outlay (no mortgage.) And prices here are more affordable than most major cities around the world, part of the reason we decided to buy. We bought in the building where we already rented, so were familiar with the building & how it is run, & the neighborhood suits us well.
Mine was full, no room for my Thai visa. I was moving in a week. I emailed the US embassy in a panic & they told me to come the following day for emergency passport. I had never heard of it, but apparently it’s common to those in the travel industry - I carried my old passport along, no questions from airlines, hotels, immigration in Thailand.
The emergency passports work - they are valid for one year. After you travel you can apply for normal passport replacement at the US embassy in Thailand. I used one when moving to Thailand - I got it in one day from US embassy in Hong Kong where I lived at that time. Not sure where you would get the emergency passport in the US though.
I don’t know for sure - but my emergency US passport was accepted at Thai immigration when I arrived. Is your emergency passport expiring before the extension ends?