Not qualified to give advice here. But I have already had 3 extensions based on marriage they look for 400k in bank account 2 months prior to day of application. The home visit is always for a first application but I am sure they can do it anytime it's really up to them.
I move between Chiang Rai and Koh Phangan. When I lived in Chiang Rai I hated it too quiet and rural. So I built on Koh Phangan and thought I would be happy around Western people and services etc. But I have learnt the people of the North are genuinely lovely people and the weather is cooler. We will eventually rent out our home here on KP and move back to Chiang Rai to retire. They also have great hospitals and medical care in CR that's my genuine opinion.
That's a fact my wife had a semi serious invasive procedure done a a Bangkok hospital. It cost 130k but the service was top class from start to finish. But I paid cash and had to be paid before admission. But insurance for over 65 is impossible here.
I come from a health care background and Public Service hospital are ok and get the job done with no frills. The private sector are very much a business and charge you well for a good service. Private insurance if you can afford it but any preexisting not covered as in blood pressure no cardiac care etc. I am on a marriage extension and it was no problem just lots of forms thankfully my wife looked after everything i became the stupid farang.
Just a small tip Bob get your wife to fill in the forms and bring to immigration front desk for a check. We than correct what ever and go back the following day with bank letter statements etc. I never speak just let my wife do the talking she understands the BS better than me and say thank you and leave simple as......Good luck and enjoy your time in Thailand.