Leaving and entering the country is not an extension.
Extensions are done in country, at immigration offices.
You get a 180 stamp every time you enter Thailand with a DTV. Just fly to Kuala Lumpur or another nearby city and spend the weekend there, instead of sitting in a van all day to go to a border and back.
As long as you don't tell immigration, they won't know. And as of now, they don't check any details when entering the country, so just don't do extensions.
you're "supposed to" check the stamp before leaving the passport control at the airport, but if there was a miss, you could also go to your local immigration office and explain your situation. They might be able to help.
Or you could just fly out and in and get a DTV stamp 👌