Extension non immigrant O.A visa or convert to O visa

I have been following the threads but need clarification

Retirement OA visa since 2008 and extended yearly on evidence of 800,000 baht (not Thai wife)and always paid for multi re entry visa as I travel overseas often.

Next extension due 20 January 2020

I am 70 years old and have insurance in my home country which covers me here except accidents for which I have separate local cover.Seems clear that local insurance with all its expense for unsatisfactory cover will be necessary for extension to be granted.In other words the argument that insurance should only apply to new OA visas granted after 31 October 2019 but not extensions of a visa granted before that date is a mute point.

Forum comments (endorsed by local IO) suggest that I should travel to e.g. Laos and obtain 90 day O visa to return to Thailand and then extend for one year based on funds (in excess of 800,000 baht)I have had in Thai bank account for years.

Queries re obtaining O visa in say Savannaket.What evidence do I need to produce?When can I do it?Does the fact I have reentry visa valid to 20/1/20 pose a problem?

I wish to initiate the O visa asap as I am committed to travelling out of Thailand for a couple of months from 8 March 2020 and will need to extend O visa and obtain multi re entry visa before then and I understand this can only be done 30 days before expiry of initial 3 month visa.This being the case I will need O visa by 8 December.

Thank you in advance