I just did this and it was easier than expected. US Embassy in Bangkok says it takes "up to six or eight weeks" to get the passport back, but in fact, in my case, it took less than 4 weeks (and I paid for the extra travel-card too). For CM immigration, I had to copy every page with Thai stamps or visas on the old passport, bring both old and new passports, and fill out the "request to transfer stamp" form, and hand it all over. No fee to do this.

I will also be applying in Vientiane. I got a letter of reference from my Credit Union in the US, which includes a summary of my account balances as of Oct 24 (I'm applying Nov 1). AND I will be submitting bank statements for the prior 5 months (May-Sept), just for good measure.

@Samantha *********

Would you mind please sharing it with me as well? I just sent you a friend request, which will facilitate sending me the text by Messenger. (you can ignore friend request, or I will 'unfriend' you after I get the message) -- thanks!