whilst most of your answer is correct and well presented factually, unfortunately you are mistaken with regards to the directorship. You only require one or more directors which can be Thai or Foreign.
With regards to the authors question as long as the necessary business and employees are in place it is completely feasible to obtain a Visa and work permit within his timescales as long as the company is operating legitimately and has purpose
Apologies for having to correct the above
Should the author wish any further information I suggest he contacts the following
Contact the following company they have been assisting expats and overseas nationals with such matters as a firm since 2007 they have in-house Thai lawyers and a British lawyer as client care manager. They can be contacted with regards to the subject
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They can deal with the last Will remotely via email and provide instructions for witnessing if the gentleman is back in Germany 
Hi Larry, if you are to settle in Korat, then get in touch with the following the perform those services on a regular basis via the ministry of foreign affairs et cetera. I hope this helps
The firm has been working with international clients since 2007. I am the firms client affairs manager, I am a practising British Lawyer, our firm has a full in-house team of Thai lawyers with expertise in that area. Please feel free, should you wish, to email me on the following