Regarding sponsorship you need to ask first who they approve as sponsors. Some embassies only approve of employers sponsoring. Location doc - utility bill, lease agreement etc. ChatGPT very useful for a sponsor letter.
He will need to get his DTV first if you want to apply as a DTV spouse. It is ok to put down a hotel. A letter of employment from the company is needed detailing permission to work remotely in Thailand. Submitting paystubs and highlighting their deposit on a bank statement will be of great benefit.