I can answer my own question now and can share the results at least for the Sisaket office.

They wanted 2 photos and 2 copies of all the relevant passport pages and visa forms......2 of everything.

The curious thing is you do NOT fill out a specific request form, think it's aT 7. You sign your name to a great many stamped pages.

The fee they collected was 2,000 baht. I was under the impression it should be 1,900 but they gave me a very straightforward receipt which my Thai friend says appears entirely proper.

Ok great......many thanks

@Mary *******

you just MADE my day! Big smile!

@Tod ********

I need to visit the Chiang Mai airport tomorrow. I wonder if I could arrange for an appointment there saving a trip to Promenada?

I'm not optimistic that the answer will be yes.

No I have not yet gone.....should I make an appointment?

@Tod ********

But who knows the rules in July?

@Tod ********

Mid May

@Kelsey **********

my understanding is any old travel agent can deal with this task.

My experience in May using a travel agent in Siem Reap was odd but worked. They wanted a photo and usual copies of the passport. They copied six months of my bank account statements in the USA. Charged me fifty dollars or so and took it off to Phnom Penh. A week later I had the SETV. No onward travel ticket required.

Ok....makes sense.