Does anyone know if it is possible to come back into Thailand through land borders (specifically in Songkhla), or does one need to fly into the country? I am considering getting a multiple entry tourist visa instead of a single entry if this is possible.

The crossing in Songkhla and others are open now.

You might need to stay overnight instead of leaving and then turning around and coming back,

26 minutes ago, Jason1921 said:

Does anyone know if it is possible to come back into Thailand through land borders (specifically in Songkhla), or does one need to fly into the country?

Most folk with a METV exit and reenter via land to obtain their next 60 day permit. 

Keep in mind that every entry that stamps you in for 60 days can be extended by 30 days. 

At this time for each entry requires TP and 10k covid insurance.

Hopefully these requirements will soon be dropped.

Obviously your fully vaccinated.