What should I include in a letter to confirm remote work for my DTV visa application in Thailand?

Hi Everyone. I'm applying for the DTV visa through Los Angeles and I just received the 'Request for Further Document' email for supplemental documents. I work for a university currently and was hired as a full time employee 2 years ago. The offer letter itself was insufficient, so I'm now putting together more documents (Employment Verification generated electronically from our portal, and a payslip that shows I'm a remote FTE) to submit. They asked for a 'Guarantee letter from the company implies that you work remotely' so I'm putting those 3 together.

I've read that LA wants a statement clearly saying that we 'do not intend to conduct any business in Thailand or engage in business activities with Thai nationals or entities, and also that we do not seek local employment'. How can I show this? I've drafted a cover letter to state this information since the above documents mentioned does not state this piece of information anywhere. I will not go to HR to have them sign off this letter and I also don't really want to go to my director for it. Is there any other way? Does it have to include a wet signature? Can I be the one to draft it on my university letterhead? Can I sign off the letter myself?

Thank you all for your expertise in this group.