Check YouTube. There are several videos from experts. They do not look at your documents. They only have one or two minutes and it is basically based on intuition and information they already have. Travel history, long term employment, long term income and certainly that she will return. Agents and lawyers are of minimal use.
If you are already in Thailand, you may have to work with the Manilla FBU and that will take months.
While you are doing this, you may have to change your SSA address to Thailand. That may bring about Proof of Life notices every year or so depending on the type of address you do (mailing or physical address)
What is a proper visa? I enter and leave several times a year for a stay of about one week. I am not going to pay for a DTV. I live near the Cambodia border. An expensive visa is overkill.